# Multiple Power supply Guide



## SpookedJunglist

*How to use two Power supplies on one computer.*
*Difficulty rating Moderate*

Ok let me start off by stating that many of us have old power supplies laying around our house. This guide will give you step by step directions to use that spare power supply unit [PSU]. Why would you want to have two PSUs anyways? There are many reasons to have multiple PSUs for your computer. One reason is to take the load off of the PSU that supplies power to your Proceesor, thus allowing for better stability for overclocking. Another reason is so that you can power up other 12volt items without your computer examples being Peltiers, Cold cathode lightuing, external fans, and so on. One more reason is that if you have a generic PSU and need power for your new high end graphics card, you can dedicate a spare PSU to run only that item. Over all there are many reasons to have some extra power on tap, I am just going to help you get that power really cheap







.

*Supplies*
1 Spare Power Supply
2 Male pins [ need to fit the 20pin PSU molex]
1 piece of 16 guage wire 2-3 inches [5-8cm]

*Optional supplies*
1 Single Pole Single Throw switch(SPST) "Push On-Push Off"
1 4pin fan or light "for testing purposes"

*Tools Needed*
*Wire cutters [needle nose pliers work as well]*
*Wire crimpers [needle nose pliers work as well]*
*Pin insertion tool [needle nose pliers work as well]*
(If you couldnt tell all i used was Needle nose Pliers)

*Ok now on to the Fun part, Modding the PSU*

*Step: 1 Cutting the wire*

Ok now take your little piece of wire and strip the ends off.
Your wire should look like mine in the picture below.
*







*

*Step: 2* *Making your Jumper*

Take your Male pins and with your needle nose pliers crimp them onto the wires on both ends so that you can just bend it around so that the pins can touch each other.


















*Step: 3 Jumping the PSU*

Here is the tricky part, We need to find the Pins that the Motherboard uses to turn on the PSU. On most PSUs the wire that turns it on is *Green* wich needs to connect with a ground *Black.* I have created a image that shows what all the different wires do on the 20 pin connector, and have pointed out the *Power on* [*PS_ON#*]and the closest ground [*COM*]. We will use our jumper to connect them together.
Below is the image showing where the pins are located, the clip is on the right in my picture.









*STEP: 4* *Connect the dots*

Ok so all you have to do is this, with the clip to your right count 4 pins up and place your jumper in the 4th hole on the right side. Refer to image above for pin locations.









Then go ahead and take the other end of the wire and conect it to the fifth hole, Right above the one you just inserted, it should look like the image below. Refer to image above for Pin locations.









*Thats it now plug in your fan and turn it on to make sure it works.*

*Alternative Steps*
*Installing a on off switch to turn on your PSU.*

From step 2 instead of creating a jumper do the following. Take a Single Pole Single throw(SPST) "Push on Push Off" switch, And install wires to the switches posts. And on the ends of the two wires install the Pins. Then follow step 4 above to insert your switch into your PSU. Should look something like the image below.








Now that that is done you can mount your switch anywhere you would like it to be on your case.

*If you are having trouble with any of these steps please PM me and i will be happy to help you..*

*If anyone has any suggestions for this guide please let me know and i will try to add it as soon as possible.*

*Thanks*
*Spooked*


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## tw33k2514

Awesome guide helped me 100% but one question were do i get a male pin lol


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## GateCrasher_VI

http://www.action-electronics.com/molex.htm


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## tw33k2514

Quote:


Originally Posted by *GateCrasher_VI*
http://www.action-electronics.com/molex.htm

thanks becuz right now im powering my vid card with a 450 psu with a paperclip and im not sure i trust a paper clip lol


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## GateCrasher_VI

lmao, please tell me you have a fire extinguisher handy......OH FOR THE LOVE OF GOD PRETTY PLEASE!!

*sigh* see, this is why modders don't live to ripe old ages children


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## tw33k2514

lol well the paperclip is holding up fine its just scary lol


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## SpookedJunglist

i have used a staple for well over a year back in the day


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## tt_shark

LEGEND!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Im repping you dude, a saviour to all


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## SpookedJunglist

No problem, thanks for the reppage









to be honest this was the eisiest of all the things ive been working on, i just never got around to finishing it, and since there was a need i decided to complete it now


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## tw33k2514

heres a good question does it work the same for 24 pin PSU's?


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## TwEaK_MoNkeY

excellent thread mate







helps heaps

reps on its way


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## SpookedJunglist

Quote:


Originally Posted by *tw33k2514*
heres a good question does it work the same for 24 pin PSU's?

havent messed with the 24 pin PSU yet, so when i get one i guess i will have to figure that one out... but you may be able to find a diagram, and just find the power on and the ground, and the rest is the same..

Not positive but i think that the 24pin molex is identicle in molex shape it just has 4 more pins so if you follow the pin order you should be able to match them up..
20 pim molex has two different sockets in the actual connector, some are perfect squares and some are D shaped squares, that way you cant plug it in backwards...But im guessing not too many people have a 24pin PSU laying around


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## SpookedJunglist

Updating with 24pin molex adapter after i make the diagram


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## DigitalPhreak

Nice! In depth! Pics to boot!


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## SpookedJunglist

Quote:


Originally Posted by *digitalphreak*
Nice! In depth! Pics to boot!

Tanks you very much, any suggestions??
I am working on drawing up a 24pin BTX pinout diagram. but other than that did i miss anything?? SPeeling even


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## DigitalPhreak

Provide a few ideas on where or how to mount your second PSU. Other than that its very comprehensive. I might give it a try since I have an extra HDD and DVD-ROM Id like to run.


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## SpookedJunglist

Quote:


Originally Posted by *digitalphreak*
Provide a few ideas on where or how to mount your second PSU. Other than that its very comprehensive. I might give it a try since I have an extra HDD and DVD-ROM Id like to run.









Let me know if you hit any hickups during your install..
I measured the PSU its almost exactly the size of two 5.25 drive bays, if you could let me know if it fits







im at work right now, that would be awesome, but ventalation could be an issue. but i could prolly Draw up some mounting ideas, maybe even side exhuasting, but if you have a big case, then you could just place it on the bottome next to your RES and Pump..The drive bays sounds like an option. my new old case looks like i could fit 3 PSUs in just the space at the top of the case, along with BIX3 and a pump









But thats in the next guide...


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## Evil XP2400

Nicely done spooked.


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## ShawnMcGrail

Just a question. I have a second PSU (no-name) with pretty good specs running my HDD, CD, Fans, and lights. Should I leave my HDD on there? or put it on the main one


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## thenut

Id put it on the main one


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## SpookedJunglist

Quote:


Originally Posted by *ShawnMcGrail*
Just a question. I have a second PSU (no-name) with pretty good specs running my HDD, CD, Fans, and lights. Should I leave my HDD on there? or put it on the main one

If you leave your computer on it would be fine to leave it on there.. i dont know if it would cause problems if your computer is off and your hard drive is on, I will do it today to an old 2gig drive and see if it kills it or if it does anything at all..

you can do the switch if you need easy access to it to turn it off..


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## ShawnMcGrail

Well... It works fine, I just have to make sure I turn on my spare PSU before I turn on the main or I'll get no HDD boot. Thanks anyway.


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## port187

Rep point awarded. +1


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## blair

i'm wondering, can't you just join the wires form your main PSU to your secondary, so when you hit the power switch (on the front of your case) is starts em both up at the same time, this would require a pair of longs wires running through your PC (not like that a new thing)

about placement, i'd say on the base of your case, it would require some PCI slot cutting though, for this you'd want to have a second fan attached to the PSU so it doesn't put too much extra heat into your Case,


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## iwannaplaygames

its great to find my questions answered before i ask them.







now i just need to find room in my tower...


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## iwannaplaygames

blair said:


> i'm wondering, can't you just join the wires form your main PSU to your secondary, so when you hit the power switch (on the front of your case) is starts em both up at the same time, this would require a pair of longs wires running through your PC (not like that a new thing)
> 
> 
> 
> i'm not a computer guy by nature. but i can build all most ANYTHING. as long you test it before plugging it in a papper clip would work (usinig spookedjunglist idea as a refrance) its the capitors that will make you go oh @*%$!!! not the leads there only at 12vdc +/- and the amps are low. usinig spookedjunglist idea as a refrance i would say instead of conecting the PS_ON and a COM. ide remove the wires (PS_ON and a COM) from the second PSU 20 pin conector tie up or cut off the rest(not the MOLEX we want those) and attatch one half of a 2 pin conector to the PS_ON and a COM to PSU #2.
> then do the same to PSU #1, instade of removing the 20 pin conector fish the PS_ON and a COM out the back and attatch the other half of the 2 pin conector. like the MOLEX/fan plugs. this way you dont have to juggle 2 PSUs into your case you can put one in at a time then plug'em to gether
> 
> sounds like it would work
Click to expand...


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## iwannaplaygames

what do you know it did work.







no sparks every thing works off of the same switch and i got my P4 from 2.74 upto 2.88





















mabe higher tomorow

ps. tell me how to post pics and i'll show you


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## Bangas

Here is my idea:

Cut the 20pin conector off. but leave the ps-on and 1 ground wires, aswell as 12V,5V and appropriate Grnds.
Wire the ps-on and Gnd to the existing PSU so the Mobo turns both PSU's on.
Use the remaining yellow(12V) and Orange(5V) and appropriate Grnds, and put molex conectors on them.
Would this be ok??
As I dont like the idea of using pin jumpers without plastic plug/insulators.
And Id gain at leat 1 molex from the cut 20pin.

Also, could I use any of the yellow(12V), and Orange(5V) wires to power devices (ie: lights, fans)?? Or because its a switching PSU this wont work??

bangas.


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## iwannaplaygames

Quote:


Originally Posted by *bangas*
Here is my idea:

Cut the 20pin conector off. but leave the ps-on and 1 ground wires, aswell as 12V,5V and appropriate Grnds.
Wire the ps-on and Gnd to the existing PSU so the Mobo turns both PSU's on.
Use the remaining yellow(12V) and Orange(5V) and appropriate Grnds, and put molex conectors on them.
Would this be ok??
As I dont like the idea of using pin jumpers without plastic plug/insulators.
And Id gain at leat 1 molex from the cut 20pin.

Also, could I use any of the yellow(12V), and Orange(5V) wires to power devices (ie: lights, fans)?? Or because its a switching PSU this wont work??

bangas.

yeh that s what i did i removed all the non 12vdc (yellow and =black) and soldered on fan plugs it gave me 4 more 12vdc plugs. so now i have a dedacated 400w psu for my mobo and 350w for my fans and drives. it frees up all that wasted OCing power


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## Bangas

Quote:


Originally Posted by *iwannaplaygames*
yeh that s what i did i removed all the non 12vdc (yellow and =black) and soldered on fan plugs it gave me 4 more 12vdc plugs. so now i have a dedacated 400w psu for my mobo and 350w for my fans and drives. it frees up all that wasted OCing power









but wot u think about "hot-wireing" the ps-on wire from the 1st PSU for the 2nd PSU?


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## xie67

Quote:



Originally Posted by *bangas*

but wot u think about "hot-wireing" the ps-on wire from the 1st PSU for the 2nd PSU?


yes i had been pondering this same thing for abit now.

the rig/toy in my signature is in need of a PSU for the fan operation on both 3x120mm for radiator cooling 1x120mm top exhaust 4x80mm rear exhaust (2each) 4x80mm side intake (2 each).

anyways i stripped the "500w" ( 12a on 12v how people can get fooled )psu that came with one of the cases and mounted it in the lower case behind the 3.25" bay. i have basicly done the same as in ive taken the pwr/on cable and attached it to a p/button sw and attached the other side to grnd comm.

then on the front panel i have installed a LED and connected it to the 12v rail for power status, it's all too simple.

yes i know it is another sw to operate on start up ( that i'll make three now ) but as it is only running the fan's i dont see it as such a big issue. and i'm sure most on the forum would have the brains to depress another switch on startup.

connecting yr two psu's in parallel to switch of the same circuit is a risk as the psu's power up/start up differently even if same model and make, which could lead to back surges to mobo.

did not want to take the risk, much better to have as independant systems

_yet you could safely switch both PSU's together by use of a relay circuit but hey i'm lazy_


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## Bangas

so is this ok?
(attached pic showing configuration)

(errm... sorry about the crappy MSpaint pic...)


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## iwannaplaygames

i've been running this set pu for a month orso w ith no noticed ill affects. but i got my mobo for <$50 bucks and if it deie i wount be hart broken. what kind of relay setup are we talking abut and are these back surges a defanet or onyl a "well... it could happen" i'm in the recon fase of building a new rig and my new board will be a little better (







asus A8N-SLI







) so ide like to find out about any problems/solutions with a multi PSU rig









Quote:



Originally Posted by *xie67*

yes i had been pondering this same thing for abit now.

the rig/toy in my signature is in need of a PSU for the fan operation on both 3x120mm for radiator cooling 1x120mm top exhaust 4x80mm rear exhaust (2each) 4x80mm side intake (2 each).

anyways i stripped the "500w" ( 12a on 12v how people can get fooled )psu that came with one of the cases and mounted it in the lower case behind the 3.25" bay. i have basicly done the same as in ive taken the pwr/on cable and attached it to a p/button sw and attached the other side to grnd comm.

then on the front panel i have installed a LED and connected it to the 12v rail for power status, it's all too simple.

yes i know it is another sw to operate on start up ( that i'll make three now ) but as it is only running the fan's i dont see it as such a big issue. and i'm sure most on the forum would have the brains to depress another switch on startup.

connecting yr two psu's in parallel to switch of the same circuit is a risk as the psu's power up/start up differently even if same model and make, which could lead to back surges to mobo.

did not want to take the risk, much better to have as independant systems

_yet you could safely switch both PSU's together by use of a relay circuit but hey i'm lazy_


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## iwannaplaygames

Quote:



Originally Posted by *bangas*

but wot u think about "hot-wireing" the ps-on wire from the 1st PSU for the 2nd PSU?


sounds like a spark maker but if it works it works


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## Leo

Cool... Some 3 or 4 years ago i had the (at that time bright) idea to use 2 psus. Unfortunatelly, at that time they werenÂ´t so stable as they are today and i never could get a stable system (the voltages were so different that a computer could never work...)


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## M0KUJINKEN

since i can't find any male pint, (checked radioshak-result:none) so i connect te two slots with a short wire
and wrap pieces of tapes to secure the wire.

does this look safe? alto the wire isn't as thick as the psu colored wires but it's about as thick.

it dont look like the extra psu is powering much here except fans and lights.
i dont understand when u guys mention video card. do u power the video card with the mod psu?


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## systemaxd

Yes the setup you have is perfectly safe since the wire needed to jump the green and black wires only carry 0.015 amps, in more aproprite terms you are controling a transistor which needs VERY low amps to work and the volts on the green wire are only 5V. So if you had a paper clip/staple that would work fine.

As for what the extra psu you can use to power anything mainly fans, hdd's, and gfx cards. The reason for the extra psu for some is to take the load of amps off the main psu's 12V rail which may in turn allow of a higher overclock.


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## SpookedJunglist

As systemaxd stated its perfectly fine









I used a staple, Just make sure no strands of copper stray into another pin.


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## Snip3rWarrior

Can i cut the wires short and cover the ends with electrical tape so that there aren't 30 wires coming out the psu, but only the ones i need... 4 pin molexs??

i would then connect the green and black wire in side (solder) instead of having to connect it with another wire outisde, and the other wires either Un-solder from the board or cut them short so there only inside the psu..


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## SpookedJunglist

Sorry that i didnt catch it yes that would be fine. but make sure none of them cross while doing this because you could short out a CAP and cause a little spark







what you might want to do would be to cut the wires individually from the PCB in the PSU and then solder a panel switch green and black then install the panel switch into the PSUs case







that would look awesome


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## Frost

2 questions. First would be is there any fire hazard to this? Basicaly just the fact that the PSU is not attached inside a case and just hanging out. If say it was on the rug or something of that sort like your picture shows. Would that not be at risk of fire? The heat from the PSU to the carpet perhaps. Or say the 20 pin wire fell to the carpet with that jumper wire hanging out, it couldn't cause a fire?

My second question would be, what would be the best way to connect this PSU to your equipment inside the case? Stick the wires through an empty PCI slot? I would think that might hurt your air cooling flow. Though I don't see where else to put it, so it does not look like crap, and have a wire hanging out of some odd spot(FDD bay?) heh.


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## SpookedJunglist

Quote:



Originally Posted by *Frost*

2 questions. First would be is there any fire hazard to this? Basicaly just the fact that the PSU is not attached inside a case and just hanging out. If say it was on the rug or something of that sort like your picture shows. Would that not be at risk of fire? The heat from the PSU to the carpet perhaps. Or say the 20 pin wire fell to the carpet with that jumper wire hanging out, it couldn't cause a fire?

My second question would be, what would be the best way to connect this PSU to your equipment inside the case? Stick the wires through an empty PCI slot? I would think that might hurt your air cooling flow. Though I don't see where else to put it, so it does not look like crap, and have a wire hanging out of some odd spot(FDD bay?) heh.


Well some cases actually have a spot for a second PSU. Most do not though. I personally had mine sitting in the location below my hard drives using your PCI slot method. Case temps were very high in that config. I am not running two PSUs at the moment, but I used the same method to create my UV pen mod FAQ. I needed it to run the UV lights to show off the pen mod. I think leaving it on the carpet would be fine. PSUs dont usuallu run too hot to touch. And as for the staple, I touched it and it wasn't even warm. I think it is very small amount of voltage.

I would suggest running it outside the case for better cooling. Maybe on top or under it?? Get creative. I am sure you can find a place for it.

Your pal
Spooky


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## Spyderwalk

Alright, so I got this 300 watt power supply hooked up along with a 500 watt power supply. I've got a Radeon 800xt that requires two power supplies, one from the AGP slot and one from the power supply. Was wondering if anyone would think its a bad idea to have both power supplies hooked up to it. . meaning one to the motherboard that supplies power to the AGP slot and the other PSU supplying power to the GPU via the power input? Can I fry my card?


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## SpookedJunglist

I would recomend powering your GPU and CPU on the 500 watt. And all other peripherals off of the 300watt. That way they get clean power. And drives dont usually care about voltage fluctuation.


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## Adeoliver

I must say this not only works on the intended application, but it makes a very cheap and powerfull power supply for a DC charger that I use on my Radio control hobby.


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## Chosen

Yeah i have a little 250W rigged up to a knife switch works great i scraped the 20 pin connector tho


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## jdubya

Thanks for this - I had a 450w PSU laying around and followed your guide now i have it powering my fans and my lighting.

I had 2 other psu before, but they were fried before i even tried to use them, i just used this guide to test them to see if they were really dead.


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## MrExtremeDK

First I'll thank all you guys for all the good ideas!

I'm bilding a extremly compact DesktopPC based on the D.Vine5 case with a Athlon64 FX-60, 2x512MB OCZ PC5000, 2x WD Raptor 74GB, 8x 400GB, 1x DVD-Burner, 1x ATI X800XT, 1x ATI X1900XTX. The big issue here is the power, so I'm making a custom backside so I have 125mm (H) x 90mm (W) x 250mm (D) space for powersupplies, but does anybody have any good ideas how so solve this?


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## hen3rz

Anyone know how to do this with an AT-Style Power Supply???


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## cluterl1214

The silverstone 7 is made for this purpose 2 psu slots are better than 1. I never much cared for redundant power myself, so it just made since to put something in the second slot just to power the quad sli. The Silverstone 7 even includes all the hardware nescessary to make the dual psu work. One problem some people my have with the siverstone 7 is if your psu has short wires you may not be able to connect to the mobo since the psu slots are in the bottom of the case.


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## Valllldondo

Where does the other PSU go then seeing how cases r not designed to hold 2 PSU's...

anyone got link for cases that hold 2 psu's?


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## mrjminer

You just saved me $102.92. I owe you 4.1168 sexual favors--or 1 rep!


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## hazara

Quote:


Originally Posted by *hen3rz*
Anyone know how to do this with an AT-Style Power Supply???

AT styles have their own switch. It directly switches the AC power so be careful!


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## muymoo

how does your second psu turn on if i dont have an on/off switch? or where do i connect it to the mobo. I have a antec truepowerII 550W and then my second is a generic 500W with 20 pins.
thanks
nice instructions


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## Le_Loup

Yeah i've got an old 200watt psu that ran my pc fine, I upgraded to a 350watt just to handle the 2 pci video cards, x-fi, 2x250gb drives,, 2x cdrom drives, floppy, and mobo, and 2x40mm fans, 2x80mm fans, and yeah.... It may eventually be a drain... So this will help me alot! +Rep for ya mate! Thanx!

Le_Loup


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## Le_Loup

I know, I know, double post, BUT

I tested this out! With a simple 200 watt psu, a 40mm "pentium 1" cpu fan... (found one, hehehehe), and some old wire thin enough to fit in the 20pin connector things, (barely, lol it was a tight fit).

It was simple metal wire, nothing to fancy, but did the job.

I plug'd everything in, EXCEPT the main power cable from the powerbar. (Left for last).

I "removed" all flamable objects away from the powersupply, so as to make SURE it's moderately "fire proof" ish....

I plug'd in the fan, rigg'd the 20pin connector with the wire (it was like almost 1 foot long, but meh, didn't want to crimp or cut it to much more, barely made 1 end to work...and a 2nd was faster...fortuantely...).

Once all rigged, then I plug'd the power cable direct into the powersupply spot, THEN plug'd it into the "power bar". The fan "turned on" 1-2 seconds later tops, I ran it for 1-2 seconds, and amazingly enough, I have to say, it worked







(No fancy connectors were required, though it's a good idea to do that, I didn't need to, in this BRIEF test).

After testing, I unplug'd it, I didn't want to "prolong" test it... because I don't think that the wire was "useable" continually with it... (figured it would be unwise to do so, especially not knowing what rating the wire was).

Also, I want to say, awesome tut, did the job, fantastic! Thanx!

Definately + rep material!

Le_Loup


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## SpookedJunglist

Quote:


Originally Posted by *Le_Loup*
I know, I know, double post, BUT

I tested this out! With a simple 200 watt psu, a 40mm "pentium 1" cpu fan... (found one, hehehehe), and some old wire thin enough to fit in the 20pin connector things, (barely, lol it was a tight fit).

It was simple metal wire, nothing to fancy, but did the job.

I plug'd everything in, EXCEPT the main power cable from the powerbar. (Left for last).

I "removed" all flamable objects away from the powersupply, so as to make SURE it's moderately "fire proof" ish....

I plug'd in the fan, rigg'd the 20pin connector with the wire (it was like almost 1 foot long, but meh, didn't want to crimp or cut it to much more, barely made 1 end to work...and a 2nd was faster...fortuantely...).

Once all rigged, then I plug'd the power cable direct into the powersupply spot, THEN plug'd it into the "power bar". The fan "turned on" 1-2 seconds later tops, I ran it for 1-2 seconds, and amazingly enough, I have to say, it worked







(No fancy connectors were required, though it's a good idea to do that, I didn't need to, in this BRIEF test).

After testing, I unplug'd it, I didn't want to "prolong" test it... because I don't think that the wire was "useable" continually with it... (figured it would be unwise to do so, especially not knowing what rating the wire was).

Also, I want to say, awesome tut, did the job, fantastic! Thanx!

Definately + rep material!

Le_Loup

Thanks but what is a rep point









Spooked


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## Le_Loup

*Re: Rep*

Probably because your a director of sorts, reason why you don't see rep, is because you are the rep, hehe. aka Reputation points. Do you see a clickable thing on me, re: rep? If so, that's what it's about, otherwise we'd +rep you if it was possible









Le_Loup


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## metalmodman

I hear this coud be bad some thing to do with some thing needing to be in sync and grounded is that true?


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## Le_Loup

Nah, not really, see, the power cable itself has a grounding wire, and if you wish to, add some ducttape, or put the switch in, etc, create it however it best works for you. If you want to have the 2nd or more psu's floating around, go ahead, I just stuck it in an olllddd pentium 1 or 2 case... So it kinda made it easier to mount, etc.







(Old beige white thing...evill...hehe)

Le_Loup


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## ethos

Could you connect up a small LED to something on the PSU? I was thinking that you could hook up the third pc case LED so that it will turn on and indicate that the PSU is running.

But not really sure if that will give it too much voltage and blow it away..

The led lights are designed to connect to the mobo front header panel


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## Le_Loup

My first thoughts,

1. Cathode stick or LED stick would do the trick, (molex connector provided with such a device).

2. Find some old, ancient 40-80mm fan from someone's old ancient pc... plug it in, turn on power, hear it spin good, don't, turn it off, it wasn't plug'd right.

3. Smile after 1 & 2 are either done or at least one is







Should work if done right









Le_Loup

P.S. Shouldn't blow up the current known universe, and then some...hehe My psu didn't do that... yet...^_^


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## metalmodman

what about noise im not talking about sound.


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## Le_Loup

Like rattling around? stability? Um, interference with other wire's? I highly doubt it, Though I haven't used more then 2 psu's as of yet. But I believe it's decently quiet overall.

Le_Loup


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## Hemato

Thanks for the guide! The idea sounds useful and it's also an excuse to install some more sexy switches in your case. I'm going to try this out in my secondary system and see how it goes.


----------



## killerfromsky

just added my 2nd power supply in my system








it works great; now I can turn of my fans+lights when ever I want

I had to dremel a place for the psu, in the 3.25" bays; and it was very tight (no more then 2mm) in my case, but it works, and I love it

Thx!

too bad I need to do 2x the cable management


----------



## SpookedJunglist

Quote:



Originally Posted by *killerfromsky*


just added my 2nd power supply in my system









it works great; now I can turn of my fans+lights when ever I want

I had to dremel a place for the psu, in the 3.25" bays; and it was very tight (no more then 2mm) in my case, but it works, and I love it

Thx!

too bad I need to do 2x the cable management










Glad it worked out for you. If you really want some good cable management you should make a part that allows you to plug in home made 4pin molex cables into it. and that way it will be somewhat modular. but you would be able to plug in everything in a better place.


----------



## boddis

Are there supposed to be any images in the guide?


----------



## DuckieHo

Quote:



Originally Posted by *boddis*


Are there supposed to be any images in the guide?


On the first post.... wait till the pics load?


----------



## boddis

Quote:



Originally Posted by *DuckieHo*


On the first post.... wait till the pics load?


It worked with Opera. Don't know why they never showed with Mozilla.


----------



## Le_Loup

They show up for me in I.E.7, and Opera, and Netscape (scary), and FireFox easily, Maybe check your seting's.

I still say an impressive tutorial!


----------



## boddis

This is great stuff, simple and brilliant. 
I came across another guide like this one. Any thought of the extra wiring being done there? Is it "extra" safe or a waste of time?


----------



## {LSK} Otacon

I tried this experiment a while ago, before i was a member here, with a 6800 graphics card. And it didnt work. I read the instructions here, and i did it the same way, but the video card beeped if it didnt turn on the exact second as the motherboard. And so then it wouldnt work at all. But it worked fine for my drives and everything, except the hdd, that as well had to turn on with the motherboard.


----------



## Koffee

This is a sweet guide. Defiantly will remember it.


----------



## SpookedJunglist

Quote:


Originally Posted by *{LSK} Otacon* 
I tried this experiment a while ago, before i was a member here, with a 6800 graphics card. And it didnt work. I read the instructions here, and i did it the same way, but the video card beeped if it didnt turn on the exact second as the motherboard. And so then it wouldnt work at all. But it worked fine for my drives and everything, except the hdd, that as well had to turn on with the motherboard.

I have yet to try it on anything other than drives and what not. I really prefer to keep my GPU on the same PSU as CPU. Usually that power supply is stronger anyways and more stable. When I did this My second PSU did not have an active PFC.


----------



## slytown

Just put some electrical tape around the paper clip and you should be fine.


----------



## slytown

Sweet. Now I have 1100 watts.


----------



## DuckieHo

Quote:


Originally Posted by *slytown* 
Sweet. Now I have 1100 watts.

Not true. You have to consider load balancing.


----------



## AmericanNightmare

Nice guide! I had been wondering if it could be done so I tried it out for the heck of it,added a cheap 450 CoolMax i had laying around. Worked perfectly i ran my HDD's and optical drives for a day w/it then took it off b/c well....i had no need for 450w devoted to my drives and it made no difference in my overclocking stability but now i know in case i ever need it. I even had a pretty little chromed switch laying about to make it extra fancy.


----------



## redsunx

Just wondering, would It be possible to have the other psu powering components i.e. hd and cd drive safely? I mean like hook it up to the hard disk and cd drive, and the other on the motherboard cpu etc and boot up fine? IF this makes no sense just ask for me to clear it up


----------



## Le_Loup

Couple thinglets,

I think it CAN work, in all "sense" it seems accurate, power them all, all good.

However, what I was told through pm's and other chat's, discussed in the past, i'd recomend AGAINST having the HARDDRIVE on a seperate power line to the psu powering the mobo... However, all fan's, cooling, special effects, can go on 1 dedicated power supply, then you can power the rest on the primary psu. Reason I suggest a seperate line for all cooling, why hog the amp's and power on that? And they can run "independant" from the main motherboard anyways.







Plus cooling before, get's the "stale" air from leaving it alone for the night or day out so the boot is fresh and smooth. My thoughts though,

Le_Loup


----------



## redsunx

Just FYI, this works on 20+4 pin psu's.


----------



## Traeumt

Great guide thnx


----------



## Mr.N00bLaR

Hmm.. AT version of this guide?


----------



## psychophat

Uber guide as always..., snipped the green and black following the diagram and used a short wire to test and poof it ran. Replaced the short wire with an old AT switch (push on/off trigger thinggy) and it works. But encountered a nag with the HDD's, here's the story.

One of my SATA now has an consistency failure, error or whatever check everytime I boot up with XP.

Initial test after completion: Tested 2nd PSU on fan, works great.

2nd test: Tested 2nd PSU on fan + DVD-ROM drive, fan works and DVD-ROM drive able to boot and run applications.

3rd test: Connected all HDD 1 PATA and 2 SATA on it without the fan + DVD drive. Experienced a glitch while booting, it suddenly locked up. The XP OS is on the 1st SATA with 3 partitions. Rebooted system, HDD's still connected to the 2nd PSU and still it wont continue to the login screen.

Conclusion: Disconnected all HDD's from 2nd PSU and connected it back to the main 500W PSU and booted up okay but encountered several inconsistency checks on 1st SATA, continued to Desktop and ran some stuff to see it works. Copying tends to be slower from 1st SATA to 2nd for some unknown reason. Rebooted several times after that and now it keeps on prompting the consistency check before loading the OS everytime.

Did I miss anything?








The 350W 2nd PSU with switch works with my fans and DVD-ROM but experiencing somewhat a low power when it comes to the HDD's especially with the SATA's. Has anyone encountered any hick-ups with SATA drives when connected to 2nd PSU? Or is my 2nd PSU kicking the bucket already? Or should it work fine with SATA's too?


----------



## marcusnerison

i have a power supply that plugged directly into the mother board can you help me make it useable ? it has the male pins instead of female so it is kinda backwards


----------



## marcusnerison

it also is 24 pin


----------



## marcusnerison

ok i got it now i just need a way to hook the cables up since they are not built in which pins do i use?


----------



## marcusnerison

ok i did it finally it was actually easy and i used a toggle switch


----------



## _Trev

I may have to do this when my new Graphic Card arrives. pushing 305W when it requires 400W minimum.

Thanks for your guide!


----------



## Heavy Light 117

this worked like a charm thanks


----------



## N2Gaming

Ok this is probably an old thread but I read every post as I am interested in doing this w/my [Project] Black N Blue. I am wondering what makes the power supply know to turn on and how the power button works. does the mobo have a charged capacitor that supplies low voltage/current to the power switch and when you push the momentary power button it in turn sends a signal through the already charged mobo circuits and finally sends a signal to the power supply to turn on. So my question is this. when you push the power button again it tells the mother board to turn off and that same circuit in the mobo tells the power supply to turn off. Ok if your still following me on what I'm thinking then wouldn't the mobo just supply both power supplies with the same on and off circuit with in itself. I don't understand how the power supply turns on and turns off. Is there a separate pin for the off circuit or is there some kind of temporary surge stretching all the way from the chassis power button to the power supply. If this is the case I don't see how having a jumper wire to pin 14 and 15 would hurt the mobo. If I understand it correctly the mobo only supplies a momentary current to the power supply each time power button is depressed for on or off. or is this wrong. So If both power supplies were jumped together via pins 14 and 15 then there should be no harm done. Please if you are confused by what I'm thinking then that means I'm not alone. I guess what I'm trying to figure out is the mobo suppling a constant continuity to the power supply or is it a momentary signal every time the power button is depressed? Can any one clear this up for me??? I'm hoping to turn both power supplies on and off with the push of one button, Thanks here are some of the links referenced a couple of posts earlier in this thread
http://www.burningissues.net/how_to/power/theory.htm
http://www.burningissues.net/how_to/power/adaptor.htm


----------



## shinji2k

Quote:


Originally Posted by *N2Gaming* 
Ok this is probably an old thread but I read every post as I am interested in doing this w/my [Project] Black N Blue. I am wondering what makes the power supply know to turn on and how the power button works. does the mobo have a charged capacitor that supplies low voltage/current to the power switch and when you push the momentary power button it in turn sends a signal through the already charged mobo circuits and finally sends a signal to the power supply to turn on. So my question is this. when you push the power button again it tells the mother board to turn off and that same circuit in the mobo tells the power supply to turn off. Ok if your still following me on what I'm thinking then wouldn't the mobo just supply both power supplies with the same on and off circuit with in itself. I don't understand how the power supply turns on and turns off. Is there a separate pin for the off circuit or is there some kind of temporary surge stretching all the way from the chassis power button to the power supply. If this is the case I don't see how having a jumper wire to pin 14 and 15 would hurt the mobo. If I understand it correctly the mobo only supplies a momentary current to the power supply each time power button is depressed for on or off. or is this wrong. So If both power supplies were jumped together via pins 14 and 15 then there should be no harm done. Please if you are confused by what I'm thinking then that means I'm not alone. I guess what I'm trying to figure out is the mobo suppling a constant continuity to the power supply or is it a momentary signal every time the power button is depressed? Can any one clear this up for me??? Iâ€™m hoping to turn both power supplies on and off with the push of one button, Thanks here are some of the links referenced a couple of posts earlier in this thread
http://www.burningissues.net/how_to/power/theory.htm
http://www.burningissues.net/how_to/power/adaptor.htm

A power supply has a rail called the 5VSB (SB = stand by). This is on a separate circuit to it's main rails (12V, 5V, 3.3V). The thing with the 5VSB is that it is always on when the PSU is plugged into the outlet. It is constantly supplying power to the motherboard.

There are two ways to turn a PSU on. Either physically jump wires 14 and 15 or use a momentary switch connected to the motherboard which basically jumps wires 14 and 15. The motherboard isn't constantly supplying power to the PSU through this, is it just a circuit that is completed with a momentary switch to tell the PSU to turn on. Once a motherboard detects that the power supply is giving it power it starts its boot sequence. This may not be a completely accurate description of the motherboard/PSU relationship, but I know the way a PSU is told to turn on is through completing the 14/15 pin circuit (well, pin 14 and any ground). If you want to turn both PSUs on with the same switch, you need to use an adapter plugged in between the main PSU ATX plug and the motherboard which are not easy to find. Something like this:



It's essentially a 24-pin extension cable with an extra set of 14 and 15 pin wires spliced in. That way both PSUs get the power-on signal from the same switch.


----------



## N2Gaming

ok so essentially if they both turn on at the same time then they would both power off as well just from jumpers 14 & 15?


----------



## shinji2k

Quote:


Originally Posted by *N2Gaming* 
ok so essentially if they both turn on at the same time then they would both power off as well just from jumpers 14 & 15?

Sorry, I explained that a little wrong. Pins 14 and 15 are not a momentary circuit. They have to be connected for the PSU to run. Once you undo that, the PSU will shut down. So, the momentary switch connected to the motherboard, triggers the mobo to complete the circuit until the momentary switch is hit again or you shut down through windows. When the mobo gets the signal to shut down, it will break the circuit and the PSU (or multiple PSUs if they are both wired to pins 14 and 15) will shut down. I hope I explained that well enough. That's sounds a little disjointed, probably could have worded it better







.


----------



## N2Gaming

Thank you. That is the answer I was looking and hoping to get. now I just need to find out if I need some kind of resistor or diods wired in so the two power supplies can't interfear with each other and if so how to go about doing it.


----------



## shinji2k

Quote:


Originally Posted by *N2Gaming* 
Thank you. That is the answer I was looking and hoping to get. now I just need to find out if I need some kind of resistor or diods wired in so the two power supplies can't interfear with each other and if so how to go about doing it.

Aside from the 14/15 pin adapter, the two PSUs don't need to be connected at any other point. Just plug your primary PSU into the main mobo connector and split up the loads from there. The big thing is where you plug each thing in. Each PSU needs to have a minimum load on the 3.3V/5V rails. The motherboard and ram will provide enough load to the primary PSU, but the secondary will need a load on the 3.3V/5V rails from HDDs or optical drives (at least 1 of each or 2 of one type for enough load). If you don't take into account the minimum load on the 3.3V/5V rails, the PSU will not operate properly and the lifespan will be reduced, sometimes drastically. Once you have ensured that each PSU is getting enough 3.3V/5V, split up the components that rely on 12V proportional to what each PSU can provide. This would be things like fans, 4/8-pin CPU and gfx cards. Once again, both PSUs need some kind of 12V load much like the 3.3V/5V rails. If you need help, just list what you want to run and I could help split the loads up for ya.


----------



## N2Gaming

I think I get it. so as long as primary psu has all 3/5/12v supplies under load and the secondary psu has them under load as well then both psu will be used the way they were intended/designed to be used and both psu will be happy and last longer


----------



## shinji2k

Quote:



Originally Posted by *N2Gaming*


I think I get it. so as long as primary psu has all 3/5/12v supplies under load and the secondary psu has them under load as well then both psu will be used the way they were intended/designed to be used and both psu will be happy and last longer










Bingo


----------



## N2Gaming

was his name oh


----------



## reaghcharles

Awsome man total rep cheers. I just combined a 550 with a 650 thanks to you mod on*cheers*


----------



## 91743

I have done pretty much the same thing as you did. EXCEPT I tapped in to the green and black wires on the power supply thats in the case, so when I turn on the pc they BOTH go on. I use 1 supply for the board and CPU, and the one outside for all the other drives i use. When I hook the green and black wires from the 2 power supplys together they both operate together when the pc is turned on.


----------



## bert02

could u tap into the other power supply so it turn off and on when turning the computer on instead of always on or with a switch
edit didnt c there was another page

what sort of psu could u use then if u were just running a graphics card on it then or 2 in sli would a 500w be sufficient to run a gtx280 or 2 8800gts or even 2 gtx260


----------



## minitt

Quote:



Originally Posted by *{LSK} Otacon*


I tried this experiment ..., with a 6800 graphics card. And it didnt work. I read the instructions here, and i did it the same way, but the video card beeped if it didnt turn on the exact second as the motherboard. And so then it wouldnt work at all. But it worked fine for my drives and everything, except the hdd, that as well had to turn on with the motherboard.


I WAS afraid of something like this could've happen. I dun knw how he setup his PSU's.

But if He could simply join the slave green to main psu's green (same for black ground) the lag would not take place.

Any one tried or have any experience on this????
plsss share...


----------



## shemer77

Ok so I am going to try this out, I was thinking about purchasing this
http://www.frozencpu.com/products/56...ter_Cable.html

If I purchase that, thats all I need right, no need to do the steps on the front page?


----------



## smokey888

ok right so im going to attempt this but i really dont know where to get the male pins im in the uk and need some one to tell me an ONLINE shop to get them or if u live in dudley somewhere in the surrounding areas







lol


----------



## Error 404

Quote:



Originally Posted by *smokey888*


ok right so im going to attempt this but i really dont know where to get the male pins im in the uk and need some one to tell me an ONLINE shop to get them or if u live in dudley somewhere in the surrounding areas







lol


You don't _need_ the pins, it's just to make it prettier, and you can barely notice it anyway. Just tin the pins (if you don't know how, just twist the strands together so the stranded wire is a lot stiffer at the end *awkwardish sentence*) and stick them in without pins. It'll work just fine, and be a lot cheaper


----------



## spazbob

I want to try this to save buying a bigger PSU, but I can't risk my rig.

Only one poster has mentioned the possibility of sync issues, and another one has mentioned that you have to load them evenly to avoid shortening the lifespan.

Can anyone else support these statements? I was only planning on putting fans on my secondary PSU and perhaps my optical drive.


----------



## shinji2k

Quote:



Originally Posted by *spazbob*


I want to try this to save buying a bigger PSU, but I can't risk my rig.

Only one poster has mentioned the possibility of sync issues, and another one has mentioned that you have to load them evenly to avoid shortening the lifespan.

Can anyone else support these statements? I was only planning on putting fans on my secondary PSU and perhaps my optical drive.


A few fans and an optical drive isn't much of a load. Is your primary PSU so weak that it can't handle the 30-40W at most from those?

There can be sync issues between the mobo/cpu/video card if they aren't turned on at the same time. That is prevented by wiring pins 14 and 15 from both units to the same switch/24-pin ATX connector. I can't really confirm the other question since I was the one who wrote it.


----------



## MintMouse

Quote:


Originally Posted by *shemer77* 
Ok so I am going to try this out, I was thinking about purchasing this
http://www.frozencpu.com/products/56...ter_Cable.html

If I purchase that, thats all I need right, no need to do the steps on the front page?

Anyone seen anything like this in the U.K? Links if so..?


----------



## MAD_J

Great thread, bookmarked for later use!


----------



## drew630

Ok, noob'ish question:

Will these pins work:
http://www.radioshack.com/product/in...3&tab=features


----------



## N2Gaming

Quote:


Originally Posted by *drew630* 
Ok, noob'ish question:

Will these pins work:
http://www.radioshack.com/product/in...3&tab=features









It depends on what you try to plug them into. I'm sure my boat won't like em much.







Any PC should use those just fine.


----------



## Threefeet

Quote:


Originally Posted by *N2Gaming* 
It depends on what you try to plug them into. I'm sure my boat won't like em much.







Any PC should use those just fine.

lol









I don't think they will fit though. The guide says molex pins, but that's an old PSU he's got there. I had to use bare wire for mine but it's all good once you tape it up right


----------



## drew630

Quote:


Originally Posted by *N2Gaming* 
It depends on what you try to plug them into. I'm sure my boat won't like em much.







Any PC should use those just fine.

Yeah, those pins don't work. They were freak'n huge, lol.


----------



## N2Gaming

Sorry, it looked good from my screen.


----------



## trueflu

Hmm I've looked threw this thread for a while and my question really hasn't been addressed.

Can I run a gpu's 2 6pin connectors from a slave power supply?

Would I turn on the master and then the slave, vice versa, or would it have to be simultaneous?

Additionally could I power one six pin with the master and the other with the slave?


----------



## Enigma8750

if you hook a relay from a 12 volt from your source PSU and the (Power on) green wire leg of the secondary. Then run a 10 ohm 100 watt resistor from the common to the 5 volt load of the secondary PSU and then a ground from the secondary wire to the ground of the primary psu.. You have an *auto on* secondary psu that you don't have to *switch on or off*.


















Note.. the 10 ohm..100 watt resistor between pin 9 and ground is not always needed. some psu's look for a load before allowing the PSU to power up.. so get the relay and the 10 ohm 100 Watt resistor at your local radio shack. The relay is 12VDC volt and has four leads coming from it. Two from the primary PSU you and two to the Secondary. When PSU 1 Powers up .. the secondary starts up too.. and when it shuts off.. the secondary shuts off.


----------



## Boomstick68

Wow, great thread. I am thinking of upgrading my graphics card to the Radeon 4890, but I don't want to buy another PSU as well. I currently have what is in my sig running everything, but I have a basic 250W pulled from an old E Machine years ago. Is the 250W enough to power the 4890? I know it requires two 75w six pin. I know the second PSU needs to be wired with the main one thats no biggie, I've located an adapter, but I'm just wondering if I can use this old PSU.








[/URL][/IMG]


----------



## Threefeet

Quote:


Originally Posted by *Boomstick68* 
Wow, great thread. I am thinking of upgrading my graphics card to the Radeon 4890, but I don't want to buy another PSU as well. I currently have what is in my sig running everything, but I have a basic 250W pulled from an old E Machine years ago. Is the 250W enough to power the 4890? I know it requires two 75w six pin. I know the second PSU needs to be wired with the main one thats no biggie, I've located an adapter, but I'm just wondering if I can use this old PSU.








[/URL][/IMG]

I don't think it will work, tbh. Your 12v rail only supplies 13A whereas I've read the 4890 requires upwards of 22.5A.

You should probably try to sell your current PSU and upgrade.

EDIT :: unless you're talking about splitting the required 12v power between the two PSUs, in which case I have no idea if it'll work


----------



## shinji2k

The 4890 uses about 8A from the PCIe connectors for gaming, 12A max from Furmark.


----------



## Boomstick68

Quote:



Originally Posted by *shinji2k*


The 4890 uses about 8A from the PCIe connectors for gaming, 12A max from Furmark.


So, it would power it but the PSU would be pushed to the limit.


----------



## Threefeet

Quote:



Originally Posted by *shinji2k*


The 4890 uses about 8A from the PCIe connectors for gaming, 12A max from Furmark.


By PCIe connectors you mean from the board, right?

The 12v connections are going to be the dealbreaker here. It's very unlikely his current PSU can't handle the current draw from the mobo.


----------



## shinji2k

It may be able to power it, but there's always the problem of heavily cross-loading a cheap group regulated design. You can't nearly max out the 12V rail without some load on the 3.3V and 5V rails. Well, you can but don't expect voltages to be in spec or it to last very long.

Quote:



Originally Posted by *Threefeet*


By PCIe connectors you mean from the board, right?

The 12v connections are going to be the dealbreaker here. It's very unlikely his current PSU can't handle the current draw from the mobo.


No that is 8A combined from the two PCIe external connectors for gaming. It will draw about 45W (4A) from the slot while gaming and ~5A during Furmark. Furmark is pretty extreme and is the max you could ever see, but it's not really representative of gaming power consumption. 4A from the slot won't be much more than his current 8800gt.


----------



## Threefeet

Quote:



Originally Posted by *shinji2k*


It may be able to power it, but there's always the problem of heavily cross-loading a cheap group regulated design. You can't nearly max out the 12V rail without some load on the 3.3V and 5V rails. Well, you can but don't expect voltages to be in spec or it to last very long.

No that is 8A combined from the two PCIe external connectors for gaming. It will draw about 45W (4A) from the slot while gaming and ~5A during Furmark. Furmark is pretty extreme and is the max you could ever see, but it's not really representative of gaming power consumption. 4A from the slot won't be much more than his current 8800gt.


No offence, but where did you get 5A under load from? That seems incredibly low for a new card.


----------



## Boomstick68

Yup, I think my question has been answered. On paper it should work but why risk damaging my system. I could sell my current PSU, but it wouldn't bring much. I'm looking a $200 for my 4890 and another $100ish for a better PSU. Hmmm, my 8800GT just got a contract extension.









Oh, BTW Shinji2k, I'm live about an hour from you.


----------



## Threefeet

Quote:



Originally Posted by *Boomstick68*


Yup, I think my question has been answered. On paper it should work but why risk damaging my system. I could sell my current PSU, but it wouldn't bring much. I'm looking a $200 for my 4890 and another $100ish for a better PSU. Hmmm, my 8800GT just got a contract extension.










On paper it won't work









I really don't know where he's getting 8A from. Every source I could find state at least 22.5A, and sometimes even higher, under load.


----------



## shinji2k

Quote:



Originally Posted by *Threefeet*


On paper it won't work









I really don't know where he's getting 8A from. Every source I could find state at least 22.5A, and sometimes even higher, under load.


You do realize 22.5A of 12V is 270W for just the video card? That is in the range of what the gtx295 and 4870x2 draw from the 12V rail.

The 8A comes from my own testing of the 4870 and extrapolating a little bit. This review shows the 4890 to be only about 20W more than the 4870. I know for a fact that the 4870 will draw 4-5A from the PCIe slot and 7-11A from the two PCIe connectors (link in sig). The PCIe slot can only supply up to 6A anyways. The 4890 wont draw much more than 4-5A from the slot, much like the 4870, and only an amp or two more from the PCIe 6-pin connectors.


----------



## Threefeet

Quote:


Originally Posted by *shinji2k* 
You do realize 22.5A of 12V is 270W for just the video card? That is in the range of what the gtx295 and 4870x2 draw from the 12V rail.

The 8A comes from my own testing of the 4870 and extrapolating a little bit. This review shows the 4890 to be only about 20W more than the 4870. I know for a fact that the 4870 will draw 4-5A from the PCIe slot and 7-11A from the two PCIe connectors (link in sig). The PCIe slot can only supply up to 6A anyways. The 4890 wont draw much more than 4-5A from the slot, much like the 4870, and only an amp or two more from the PCIe 6-pin connectors.

You're right that the 22.5A I've seen written is too high, but 8A from the 12v rail is not enough.

http://www.overclock.net/ati/407789-...quirement.html

I haven't done my own testing though, so I shouldn't really be arguing


----------



## shinji2k

8A is just from the external PCIe, you have add the 4-5A from the slot. That puts it at ~150W. But his secondary PSU will only be supplying power to the 6-pin PCIe connectors.

And I fail to see how that thread you linked to adds anything. TDP may be 157W but TDP is hardly ever an accurate estimation of power consumption. I can draw 190W running a renamed Furmark on the 4870 and I have seen the 4890 hit 220W in a review running Furmark.


----------



## Boomstick68

I'm glad I asked before doing because it certainly isn't enough. I'm gonna look for a good single 12v rail PSU that will carry me on to my future i7 build. I have alot to learn and I'm glad you guys are around.


----------



## shinji2k

A single decent PSU with enough capacity is always a better choice than running two PSUs.


----------



## Threefeet

Quote:


Originally Posted by *shinji2k* 
8A is just from the external PCIe, you have add the 4-5A from the slot. That puts it at ~150W. But his secondary PSU will only be supplying power to the 6-pin PCIe connectors.

And I fail to see how that thread you linked to adds anything. TDP may be 157W but TDP is hardly ever an accurate estimation of power consumption. I can draw 190W running a renamed Furmark on the 4870 and I have seen the 4890 hit 220W in a review running Furmark.

TDP may not be an accurate estimation of power consumption, but a 13a emachines PSU would be very lucky to run a 4890 with any kind of stability. You even pointed out that you've seen a 4890 hit 220w under heavy load, into the territory of the dual GPU cards.

Anyway you clearly know much more about this than I do so I'll respectfully bow out of this debate.


----------



## shinji2k

Oh I'm not denying that Bestec would have trouble with it, but it mostly from the fact that it will only load the 12V rails. It's possible it could handle 8 or 9A on the 12V provided the other rails were properly loaded. But it's not easy to do that in a dual PSU setup nor all that sensible.

And Furmark is not a very good test for everyday usage. No video game can come anywhere near the numbers Furmark can load a video card to. Realistically you won't see the 4890 go much past 150-160W under just about any situation.


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## Le_Loup

Hey Spooked,

I'm making a 7 fan, 1 x 430watt psu, 4x fan controller with led etc, laptop cooler bay frame thingamajig... (It's so far in design/development stages).

I've got the fans, psu, fan controller, but i'd like to know, for this power switch I ordered Blue LED Military Style Switch , It looked like it had "3x" power connector points at the back,

Power, Acc, Ground.

I figured what power and ground is, but acc? Any suggestions if that should be both power and acc on same line?

P.S. I'm trying to find the molex pins, and can't. Tried locally homedepot, the source, futureshop, best buy, memory express.. no dice..







Any ideal suggestions?

Was thinking I could just use a slightly thicker wire, wedge it into the part there, and utilize electrical tape... But I wasn't sure how "safe" that would be long term...

Internally between psu part and the front switch (for cable management) is 12-15 inches of wire on each line (power/ground primarily).

Thanks,

- Le_Loup


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## N2Gaming

Hey Le Loup, have you tried Fry's electronics? That is of course if you have one near you. I found bare molex connectors and bare pins for wiring my own molex cables for fan headers and power connectors.

Good Luck,

N2G


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## Le_Loup

Quote:


Originally Posted by *N2Gaming* 
Hey Le Loup, have you tried Fry's electronics? That is of course if you have one near you. I found bare molex connectors and bare pins for wiring my own molex cables for fan headers and power connectors.

Good Luck,

N2G

When searching molex, it brings up headers or cables. (Neither I need). I just require a variant of the pin part, and similar wires (or I can just cut them out of a dead psu that came with a friends dead case, another story all together). Just so I can hook things up.

Contacted fry's, i'm in alberta canada, so checked info on what I can do, found out they do ship to canada (Yay!!!!!!) But they don't ship actual pc's and operating systems... Small parts (what i'm looking for) they do for sure.









If you can help me locate, or similar, i'd very much appreciate it, as i'm willing to order in 2-3 days the parts!

- Le_Loup

*Would this work?*

Or am I a tad off?


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## N2Gaming

Quote:



Quote:


Originally Posted by *Le_Loup* 
Hey Spooked,I've got the fans, psu, fan controller, but i'd like to know, for this power switch I ordered Blue LED Military Style Switch , It looked like it had "3x" power connector points at the back,

Power, Acc, Ground.

I figured what power and ground is, but acc? Any suggestions if that should be both power and acc on same line?

It's possible the ACC is for the blue led in the switch.

That switch can be used in a couple of different ways. I think the ACC stands for accessory power. The wiring could be done any number of ways. It all depends on how you want it and how much wire you want to run. The best way to determine how to best use that switch is to try it out.







j/k

Power of course is 12v+ and ground is 12v- So if you were running a circuit on that switch I think you could have the power go directly through the switch at all times from 12v+ to 12v- as a constantly hot wire or closed circuit and then the ACC you could use for an additional 12v+ circuit used w/the flip switch to turn it on and off at your will. I don't have to switch in my hands so I don't know if the continuity is always open from power to ground or if it's always off and the switch turns it on. If you dont' have a digital multi meter then I would suggest getting one that has the audio tone for testing continuity. The Ohm continuity tester comes in very handy more then you know.
Let me go dig up & look at my bag of goodies and take a few pictues w/the frys lable for part #'s so you can order what you want.







I'll edit this post w/the pictures. in a bit.

Edit: Pictures of the molex pins. I hope this is what you are looking for. The Fry's part numbers are the numbers all the way at the bottom of the white label in the lower right hand corner. I don't know if you need the male or femal pin so I gave you both.

Good Luck,

N2G


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## Le_Loup

Fantastic! Thanks! Will start ordering, pm sent re: specifics. Thanks!


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## mikhail00

ok.. i know this is an old thread.. and im going to bump it up because i got a question on this.. see i got a current system which is on my sig right now.. but im planning on adding a raid0 setup and ALOT of fans and cathodes.. so on planning on plugging in the motherboard and the gfx cards on the main PSU.. and the rest on the slave PSU.. i have 2 Gigabyte Superb 550p psu.. 1 is in my current rig.. and the 2nd one was from an old rig (which i sold)..

here are my questions.. hope some1 can help me out..

1. can i use the old green wire from a generic PSU to use it as a jumper?..

2. is it possible to hotwire the main casing switch with both PSUs?..

3. is it safe to put the PCI-E connectors for the gfx cards on the slave PSU?..


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## N2Gaming

mikhailOO, You could just purchase a mobo 24 pin PSU extention plug with the extra jumper wires already connected for close to $10.00. This way you won't have to splice into any of your PSU wiring and if they are under waranty they will stay that way.

Regarding using the PCIe power connectors from the slave drive. Ideally you would want to use the main Power supply for all of your video cards if it has enough power for them, other wise you could use the PCIe connectors from the slave PSU.

One thing to consider when doing this, you'll want to utilize all of the voltage
rails on both power supplies.i.e. 12v/5v/3.3v. You need to use all of those voltage rails to prevent premature failing of the slave PSU. If you don't use all the power supply rails then it's possible for the capacitors to go bad as well as the rest of the internal un-used circuits..

Hope this helps,

N2G


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## mikhail00

wow.. thats going to be a bummer.. i kinda dont know any hardware that i have that will utilize the 5v and 3.3v rails.. i guess i really have to buy a new PSU then.. T.T

what kinda hardware utilizes the 5v and 3.3v rails?.. coz the only thing i know that uses these rails are the MoBo.. me super noob at this.. >.<U


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## Phaedrus2129

Quote:



Originally Posted by *mikhail00*


wow.. thats going to be a bummer.. i kinda dont know any hardware that i have that will utilize the 5v and 3.3v rails.. i guess i really have to buy a new PSU then.. T.T

what kinda hardware utilizes the 5v and 3.3v rails?.. coz the only thing i know that uses these rails are the MoBo.. me super noob at this.. >.<U


Many fans use the +5V and +3.3V rails. Also hard drive motors run off the +5V rail, which is why PSUs with bad group voltage regulation will fry hard drives if overloaded (you overload the +12V, +12V drops to 11.8V and +5V jumps to 5.3V, hard drive dies). Some CD/DVD drives also use the +5V.


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## makecoldplayhistory

Came on here to double check I was correct in the mod I'd read about on other forums to use a 2nd PSU for the fans in my PC.

What nicer way to be educated than to see a sticky thread, explaining in perfect detail, every question you're about to ask.

Massive thanks to the OP.

Mike


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## lovesmyguide

Ok! Awesome guide! Exactly what I need except one question no one else has asked! I'm a complete noob to modding my pc how do I connect the second PSU for the video card, is it a connector on the mb or do I have to make a new rig for the card, or should I just move all my drives to the second PSU. And if I don't use a switch do I have to just learn the timing for plugging the second psu into the outlet? Thank You!


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## lurkingdevil

Quote:


Originally Posted by *mikhail00* 
here are my questions.. hope some1 can help me out..

2. is it possible to hotwire the main casing switch with both PSUs?..

3. is it safe to put the PCI-E connectors for the gfx cards on the slave PSU?..

those two questions are the ones i am needing an answer on too.

there might be answers to them scattered in the topic but browsing through 14 pages it just gets too confusing with mixed responses..


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## spartan2012197

I was messing around with some old psus I had in the basement and I threw together a rig where the motherboard and processor were powered by a regular Atx power supply, while the hdd and cd drive were powered with a really old power supply (not exactly sure what it's called, but it's the type that were in the original ibm pcs). What's great is that I didn't have to use any jumpers, extra wires, or any sort of modding, cuz the ibm psu has a push button power connector build right onto it to power up the rig.


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## dominique120

WOW, Nice guide!


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## Beefmuchaco

Great thread, stll working great 5 years later!! thanks now i wont be buying a new psu.. needed new case so just gona get a massive full tower


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## Scart

Quote:


Originally Posted by *SpookedJunglist* 
*How to use two Power supplies on one computer.*
*Difficulty rating Moderate*

Ok let me start off by stating that many of us have old power supplies laying around our house. This guide will give you step by step directions to use that spare power supply unit [PSU]. Why would you want to have two PSUs anyways? There are many reasons to have multiple PSUs for your computer. One reason is to take the load off of the PSU that supplies power to your Proceesor, thus allowing for better stability for overclocking. Another reason is so that you can power up other 12volt items without your computer examples being Peltiers, Cold cathode lightuing, external fans, and so on. One more reason is that if you have a generic PSU and need power for your new high end graphics card, you can dedicate a spare PSU to run only that item. Over all there are many reasons to have some extra power on tap, I am just going to help you get that power really cheap







.


thanks for the handy tip.. i wanted to see if my new psu was the culprit or the new motherboard not running my gtx... seems when i booted up the sound card(pci) was missing from the system and mouse slighty locking. so i'd say its the mobo..

thanks !


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## azurial

hi all, new here and was wondering if a second psu could be linked into one of the molex connects


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## Krusher33

Quote:


Originally Posted by *azurial* 
hi all, new here and was wondering if a second psu could be linked into one of the molex connects

You mean connect molex from one PSU to the molex of the other???

Have a camera man videotaping it while you do it...


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## azurial

Quote:


Originally Posted by *Krusher33* 
You mean connect molex from one PSU to the molex of the other???

Have a camera man videotaping it while you do it...

sorry i ment from an IDE connector lol


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## Volvo

What?


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## LiNERROR

um. that connector is much bigger than the ATX connector is expecting, be advised that you risk expanding your ATX pins to the point of loose or no contact... that wire itself tinned would be fine though...









if this is going in a machine, provided you have a common ground... you can bridge just the green wire... which can be done easily with some solid 18AWG wire plugged into the back of the ATX connector... wire wrap and soldering are also options...


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## Le_Loup

Question, Can I "splice" equally like above picture, colour wire to colour wire of 2 or more same psu's on the same connector line? Literally? So that when I press a single power button on the front of the case, it triggers both automatically? This would make it easier if I eventually put in a 12x sata connector gigabyte mobo... And want to start 12 harddrives with mobo @ the same time, and still have enough juice for say triple sli/crossfire, etc...

Even just the trigger lines spliced between the main header like above picture, for both psu's, with just one plugged into the mobo?

- Le_Loup


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## Freakn

Bump Bump,

I'd like to know the answer to this, looking to do the exact same thing.

Also, could I run all my hard drives and fan's off the slave PSU and just power them up before powering up the main PSU??

Cheers


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## Bamby

guys I can't see the pics?

thanks anyway


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## Threefeet

Quote:


Originally Posted by *Bamby* 
guys I can't see the pics?

thanks anyway

Pics work fine for me


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## Bamby

Quote:


Originally Posted by *Threefeet* 
Pics work fine for me









thank you, it's my end


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## NicksTricks007

Quote:


Originally Posted by *Threefeet* 

EDIT :: unless you're talking about splitting the required 12v power between the two PSUs, in which case I have no idea if it'll work









I am currently in the process of testing this. I have a 200w PSU and 250w PSU which I am going to try it with. I also made my own PCIe 6 pin to 4 pin molex plugs using the 20 pin mobo plug off of a dead PSU. I will have pics up soon. Theoretically it should work as the 4890 uses about 325w at full load and I'll have 450w of available power. Guess we'll find out soon enough


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## Threefeet

Quote:



Originally Posted by *NicksTricks007*


Guess we'll find out soon enough










Guess we will!

You should check out Shinji2k's posts, he knows quite a lot about this









Meaning: much more than me lol


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## NicksTricks007

Will do, thanks for the suggestion. I am almost ready to start testing. Pics of the equipment I made will be up shortly.


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## NicksTricks007

Ok, so I just finished trying out my makeshift plugs and they don't seem to work when splitting the voltage between 2 PSUs. Unless I wired them wrong, which I'm 99.9% sure I didn't cause I followed THIS for the PCIe 6pin part and THIS for the 4 pin molex part. I connected each wire to the appropriate area. The 4 pin molex was actually 3 pins cause the GPU doesn't use the 5v signal. So I took the 3 12v and wired them into the 1 12v wire on the molex cable, and did the same for the Ground. I don't think that was the problem, otherwise why would they sell THIS. I know I could have bought one, but making one was part of this project. Does anyone with working knowledge of this type of thing think that splitting the voltage between 2 PSUs (meaning I have 2 PCIe 6pin connections on my GPU, 1 adapter is going to the first PSU and the other is going to the 2nd PSU) is the issue? By the way, the 2 PSUs in question work fine, are external and separate from my main PSU which is powering everything else inside my rig.


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## Baskt_Case

Quote:


Originally Posted by *NicksTricks007* 
Does anyone with working knowledge of this type of thing think that splitting the voltage between 2 PSUs (meaning I have 2 PCIe 6pin connections on my GPU, 1 adapter is going to the first PSU and the other is going to the 2nd PSU) is the issue?

This _should_ work. Unless your having a sync issue, meaning, both PCI-e headers seeing equal power at the same time. Might be tricky depending on how you are powering up the rig.

I dont know the workings of a dual connector vid card, but I do know electricity a bit. 12 volts to each should do the trick, no matter where it comes from so long as it supplies the amperage when the card pulls on it.

First thing I would to is get out my multimeter and check continuity and resistance through all my connectors to ensure good contact. Make the connection at the card and check resistance through the header on the card as well. Put one probe in the backside of your home-made connector and put the other probe on the trace or solder point on the card. If everything checks out, turn on the PSU's and check for voltage at the appropriate traces/solder points on the card. Check all the grounds too, power is useless if you dont ground it. If you are getting 12v at all points on the card, and you have verified your grounds, I call it a bad card. Like I said, it shouldnt matter where the 12v comes from, so long as its there and doesnt back down when the card starts pulling more amps (gaming/folding).


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## h4x0rpnv

ty very much 
works as charm lol (except the strange noises )


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## Jarvillio

this is great! any suggestions on mounting the second psu in the case?


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## maxter

Hi I tried this with my PSU and heard some quiet sound, but it didn't turn on and when I plugged it back into my PC there was no reaction. tried it with another PSU and exactly the same thing, both are apparently dead. and yes I connected the green and black.
any help and suggestions would be most appreciated.


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## hazara

Not using old AT psu's are ya? Did you have any load on the powersupplies.. I have seen some before that wouldnt powerup without load.


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## veritas-truth

I have a question and a little info this thread may find interesting.

First my question: if a mobo uses an 8 pin connection for the CPU, but the PSU has 2 4 pin connectors, can the two 4 pins be used to fill the 8 pin? I have read that they can usually run on a single 4 pin connector

Now the interesting info: Car amplifiers (for speaker and subs) use 12V DC power, so you can use a PSU to power a car amp and speakers. All you have to do is make a jumper like this guide states; take any 12V output from the PSU and attach one to the 12V power and one to the Remote line (what tells the amp to power on, so you can put a switch in the path to control the amps power) then hook up your speakers and you're good to go.


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## Greensystemsgo

Quote:



Originally Posted by *veritas-truth*


I have a question and a little info this thread may find interesting.

First my question: if a mobo uses an 8 pin connection for the CPU, but the PSU has 2 4 pin connectors, can the two 4 pins be used to fill the 8 pin? I have read that they can usually run on a single 4 pin connector

Now the interesting info: Car amplifiers (for speaker and subs) use 12V DC power, so you can use a PSU to power a car amp and speakers. All you have to do is make a jumper like this guide states; take any 12V output from the PSU and attach one to the 12V power and one to the Remote line (what tells the amp to power on, so you can put a switch in the path to control the amps power) then hook up your speakers and you're good to go.


this is provided it puts out enough amperage/watts or not to much for your little car stereo setup. 12v is pretty common in daily life, most cars are 12, some older 6. mine was converted to 12 so were good









also, thread bump.


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## Phaedrus2129

Car batteries actually output around 13.6V.

And 9V batteries are 9.6V.

And AA batteries actually have a slightly higher voltage than D cells, but less mAh.


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## denydog

Quote:



Originally Posted by *Phaedrus2129*


Car batteries actually output around 13.6V.


In my experience, resting voltage typically measures 11.5-11.8. A typical charging source would roughly be 13.5-14.5

There is no exact answer due to many variables. I admit most of my experience comes from sailboat systems with adjustable multi-stage smart chargers.


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## veritas-truth

You're not going to really power a giant car amp with it, but the old 200W PSU from an old win 98 machine I had powered my 100W sony amp just fine and i had that pushing 2 8ohm bookshelf speakers rated at 30W each and an older 12" 8ohm home sub at 20W; it was a decent little system. I think I had the bookshelves wired in series together and then the sub bridged in parallel with the bookshelves so it was a 5.33ohm load since the amp was stable to 4 ohms


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## ccrunner863

I've heard a lot of places that if you do this, you need to have a constant load on the psu or you can damage it... any truth to that? I'm using a crappy 280w psu that I had laying around to power a custom slot car track







but i have an 80mm fan hooked up to one of the 5v lines (red) to give it load just in case...

Is my fan necessary? My (very limited) knowledge of electronics tells me that at the very most, all i would really need is a small load for a short time after it is turned on to charge up the caps's


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## Shub

Quote:


> Originally Posted by *ccrunner863;12997223*
> I've heard a lot of places that if you do this, you need to have a constant load on the psu or you can damage it... any truth to that? I'm using a crappy 280w psu that I had laying around to power a custom slot car track
> 
> 
> 
> 
> 
> 
> 
> but i have an 80mm fan hooked up to one of the 5v lines (red) to give it load just in case...
> 
> Is my fan necessary? My (very limited) knowledge of electronics tells me that at the very most, all i would really need is a small load for a short time after it is turned on to charge up the caps's


It depends on the unit. A group-regulated unit would require a minimum load on all rails in order to deliver stable power. A single fan on the +5V rail would not be enough to offset the problems you may encounter in a group-regulated unit when crossloading.


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## ccrunner863

Quote:


> Originally Posted by *Shub;12997276*
> It depends on the unit. A group-regulated unit would require a minimum load on all rails in order to deliver stable power. A single fan on the +5V rail would not be enough to offset the problems you may encounter in a group-regulated unit when crossloading.


So will neglecting to load the 5v rail actually hurt any of the PSU's internal circuitry? (and is there an easy way to tell if it's group-regulated?)


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## Shub

I don't know if it would hurt the internal circuitry, but depending on what effect crossloading is having in the electrical output, it may damage whatever is connected to the PSU.
I don't know if it's possible to tell if a PSU is group-regulated just by looking at the guts. If it is, then I'm not knowledgeable enough to tell. If you can't tell from looking at the guts, then you'd need a load tester.


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## Phaedrus2129

You can tell if a PSU is group regulated by looking for coils on the secondary. Basically, look at where all the wires connect to the board, next to them will be lots of capacitors and a number of large chokes like this:










Three coils = Independent regulated (safe to crossload)
Two coils = Group regulated (NOT safe to crossload)
One coil + daughterboard = DC-DC (safe to crossload (+12V-heavy crossload only--+5V crossload not recommended))
One coil = Group regulated with 3.3V regulated from +5V (probably a piece of garbage, so don't load it at all)


----------



## Phaedrus2129

Independent regulated:
Antec HCG-900









Group regulated:
SeaSonic S12II 520W









DC-DC regulated:
Antec TruePower New 750W









Group regulated with linear regulated +3.3V:
Linkworld LPSW 350W


----------



## Snowmen

Just wondering... If you jump the second PSU and plug fans or watercooling pumps on it, normally they will stay on permanently unless the PSU itself is turned off right?

Thanks


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## Joey23art

I have an 8 year old 850 watt power supply and a 3 year old 350 watt power supply. I have 2 SATA hdd, and 1 IDE DVD drive. I just purchased a video card that needs 2 6pin PCI Express connectors. (I will use the supplied Molex adapters though)
What would my ideal dual PSU setup be? Which power supply should be the main and what should each power supply power? I only have 2 fans, including the CPU fan.

Thanks.


----------



## Phaedrus2129

Quote:



Originally Posted by *Joey23art*


I have an 8 year old 850 watt power supply and a 3 year old 350 watt power supply. I have 2 SATA hdd, and 1 IDE DVD drive. I just purchased a video card that needs 2 6pin PCI Express connectors. (I will use the supplied Molex adapters though)
What would my ideal dual PSU setup be? Which power supply should be the main and what should each power supply power? I only have 2 fans, including the CPU fan.

Thanks.


Neither. Buy a new PSU.

Just because you can do something, doesn't mean it's a good idea. I plan to make some major revisions to this guide to make clear when it's a good idea to dual PSU, and when it will end in tears.


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## eXXon

I have 2 Corsair 600 watts PSU's (one is CX & the other GS) that I would like to use for my sig until I get my original PSU returned from TT.

The guide seems outdated and intended for old PSU's.....would it work for newer psu's? (the pics are all missing)


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## Puck

If you connect the green from the slave psu and the nearest ground to the corresponding pins on the motherboard connector, they will both turn on and off together both with the main switch and for hibernation.

Like stated though, there are few times when dual PSUs are neccesary or even worthwhile.


----------

