# Exactly How Does a CPU Bottleneck a GPU?



## dieanotherday

I'm very unfamiliar with this concept which is pretty logical, but I would still like to know the requirements for bottlenecking.

I'm thinking about getting a 4870 for my current computer after I get my bank account setup.


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## Grafixs

ever try putting a Pentium 4 and a 3870x2 together?, not too pretty


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## Pooping^fish

I think something along the lines of:
The cpu cant process the info or load as quick as the GPU. Or the cpu has more room left that the GPU isnt taking advantage of.
Perhaps?


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## slngsht

My cpu bottlenecks my gpu right now. it results in game stuttering


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## Chozart

Bottlenecks can occur either way. Basically what it means is that the slowest component determines the final performance in a certain application.

In gaming, for example, the GPU is the most important part. However, if you have a high-end GPU with a low-end CPU, the CPU simply can't keep up, and the CPU is the part that determines the final performance. Other way around, when you have a high-end CPU and low-end GPU, the GPU is the bottleneck.

Now, at any kind of reasonable resolution (1680 x 1050 and up), CPU bottlenecks are rare.


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## dieanotherday

I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.


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## mrtn400

Basically:

If a CPU is taking a long time to calculate where a person is at or where they're aiming, then how is the GPU supposed to draw that to the screen? It waits for the CPU to "finish" and then draws it. As simple as that.


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## Chozart

Quote:


Originally Posted by *dieanotherday* 
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.

You can't state it like that. Too many factors involved.

A CPU can bottleneck a GPU at low resolutions, but at high resolutions the tables will be turned. That's one.

Enabling AA/AF and such put more stress on the GPU, reducing bottleneck.

etc etc.


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## McStuff

Quote:


Originally Posted by *dieanotherday* 
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.

This is impossible because there is a wide range of both cpu and gpu architectures.


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## DeRock131

Think of it more generally:

If your CPU is fast think of it as water being dumped into a funnel, if the funnel opening isnt big enough water will not get through, basically hindering the flow (processes)

Its vice versa for CPU bottlenecking. There isnt enough water to feed the funnel its full flow potential.


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## CorporalAris

Here's a question: (Sorry for a little thread hijack...







) What processor should I get if I want to make sure that I don't bottle neck my 8600GT?


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## DeRock131

Quote:


Originally Posted by *CorporalAris* 
Here's a question: (Sorry for a little thread hijack...







) What processor should I get if I want to make sure that I don't bottle neck my 8600GT?

A single core at 3.00ish probably wont even bottleneck our GPU :-/

A e2140 at stock is insurance lol


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## DuckieHo

Quote:


Originally Posted by *CorporalAris* 
Here's a question: (Sorry for a little thread hijack...







) What processor should I get if I want to make sure that I don't bottle neck my 8600GT?

What game, resolution, and settings.....

A Q6600 at 5GHz should do it.


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## DeRock131

Quote:


Originally Posted by *DuckieHo* 
What game, resolution, and settings.....

A Q6600 at 5GHz should do it.

Why 5 ghz? Should't he search for an ES so he can get the 17ghz needed to run sim city 2000?


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## Chozart

Quote:


Originally Posted by *DuckieHo* 
What game, resolution, and settings.....

A Q6600 at 5GHz should do it.











I guess you still play at 800 x 600 eh?


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## slngsht




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## Betrivent

Quote:


Originally Posted by *DuckieHo* 
What game, resolution, and settings.....

A Q6600 at 5GHz should do it.

I run 47.56Ghz on my C2Octo 24/7 at .75 vCore.


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## Melcar

"Bottleneck" is such an inappropriate term, but it's now become a catch phrase. A GPU always will perform at its fullest, no matter what it's paired with. The reason someone with a 3GHz X2 has lower frames in a game (or a benchmark) compared to someone else with a 3GHz C2D (both with the same GPU) is simply because one CPU is faster than the other. Benchmarks like 3DMark show this clearly; benching the above CPUs will give you drastically different scores, but if you notice, the GPU scores would be almost the same, while the biggest difference (and what determines the final score) will be the CPU score. People say 3DMark is too CPU dependent, but that is what basically happens when you stick a faster CPU in a system... the score (gaming performance) increases.
You need both components to game, a fast CPU and a fast GPU. Of course you got variables, like gaming at high resolutions depending more on the GPU, and so forth. However, the fact of the matter is that a slow CPU does not slow down a GPU, but rather a slow CPU slows down your overall perfomance, much like less or slower RAM or a slow HDD, would decrease your overall performance.
So do not bother breaking your head trying to figure out if a new card you're planning on purchasing will be "bottlenecked" by your older CPU. Just get the fastest card you can afford.


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## TempestxPR

sorry for bringing this thread back from the dead if i put 2 260gtx in sli with a amd phenom x4 9500 2.2ghz would there be a bottleneck of any kind?


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## tipsycoma

Quote:


Originally Posted by *slngsht* 
My cpu bottlenecks my gpu right now. it results in game stuttering










An e8400 at 4ghz most definitely does not bottleneck a 4870.

The term bottleneck is so overused.


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## T D

Quote:


Originally Posted by *tipsycoma* 








An e8400 at 4ghz most definitely does not bottleneck a 4870.

The term bottleneck is so overused.

This topic is a year old.

Let's let it get buried again people.


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## Maian

Quote:


Originally Posted by *tipsycoma* 








An e8400 at 4ghz most definitely does not bottleneck a 4870.

The term bottleneck is so overused.

That post was made over a year ago... he probably did not have that setup.

Quote:


Originally Posted by *TempestxPR* 
sorry for bringing this thread back from the dead if i put 2 260gtx in sli with a amd phenom x4 9500 2.2ghz would there be a bottleneck of any kind?

It would be best to start a new thread rather than resurrect a thread that is a year and a half old.


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## BlackHoleSon

Think of it as the treads on a tank.

Many tanks have 2 treads, one on each side. Lets say the treads on the left of the tank are moving at 9 MPH and the treads on the right of the tank are moving at 6 MPH.

So just because one of the components has the potential to move at full speed, the other component is slowing it down. I for example have a little bit of a bottleneck going with my CPU to my video card, which is why im saving for a Phenom II.


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## PaRaDoX_883

iPhail @ bump. Sorry guys..


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## Clockadile Dundee

Quote:


Originally Posted by *BlackHoleSon* 
Think of it as the treads on a tank.

Many tanks have 2 treads, one on each side. Lets say the treads on the left of the tank are moving at 9 MPH and the treads on the right of the tank are moving at 6 MPH.

So just because one of the components has the potential to move at full speed, the other component is slowing it down. I for example have a little bit of a bottleneck going with my CPU to my video card, which is why im saving for a Phenom II.

That tank will be turning left.


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## codejunki

1 core per 100$ on a gpu. simple


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## TempestxPR

Quote:


Originally Posted by *TempestxPR* 
sorry for bringing this thread back from the dead if i put 2 260gtx in sli with a amd phenom x4 9500 2.2ghz would there be a bottleneck of any kind?

can someone answer this before i buy


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## BAMJ6

The only applicable way i know bottlenecking is this.

My bro's CPU/GPU is Q6600/8800 GT

I have a lesser CPU than him. If i put an 8800 GT or better in my sig rig, it will bottleneck my games


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## T D

Quote:


Originally Posted by *TempestxPR* 
can someone answer this before i buy

Those are the old gen Phenoms IIRC. Don't get them. Get at least a Phenom II X4 920 if you're going quad and AMD for gaming.


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## FSF-Foxhound

Quote:


Originally Posted by *dieanotherday* 
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.

not really, a RV870 @ 400MHz will be bottlenecked by the CPU. It does not work like that


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## 5ILVgeARX

Quote:


Originally Posted by *TempestxPR* 
sorry for bringing this thread back from the dead if i put 2 260gtx in sli with a amd phenom x4 9500 2.2ghz would there be a bottleneck of any kind?

Yes, at 1680x1050 a 2.2ghz quad will likely drop a lot of your FPS since most games are still single thread/dual. you probably need at least 3.0ghz quad. A 3.6ghz quad would greatly take advantage of your gtx 260 sli.

why not just get a single gtx 275 and try to overclock that quad a little more and save yourself from having to upgrade to 2 gtx 260 and a psu.


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## stewarttr

The GPU is waiting on the CPU to send it more work.

The GPU needs to slow down or risk getting laid off.


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## djcross+fade

Quote:


Originally Posted by *slngsht* 
My cpu bottlenecks my gpu right now. it results in game stuttering

o hell mine does that to on my 775
i get 100 fps in bf2 on my 275 along with 30 gb ocz vertex

good thing im going i7
so that i can play crysis (only played once with 4850 and 4870 in crossfire
then i sold it to buy better cooling cause my coolit pump went out







never buy there pumps they suck !!!


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## djcross+fade

Quote:


Originally Posted by *stewarttr* 
The GPU is waiting on the CPU to send it more work.

The GPU needs to slow down or risk getting laid off.









lol maybe thats what happen to me







lol good thing im a dj







didnt hurt me that much


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## voovode

Quote:


Originally Posted by *dieanotherday* 
I'm very unfamiliar with this concept which is pretty logical, but I would still like to know the requirements for bottlenecking.

I'm thinking about getting a 4870 for my current computer after I get my bank account setup.

I have an intel celeron at 2.8ghz while the gpu is a 7900GS of XFX at 512Mb, i get bottlenecked cuz simply while the gpu can get loads of graphics running, my cpu can`t read them in the correct time, that's why it`s laggy.

-the simplest sentence.


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## Alanhunt123

Quote:


> Originally Posted by *Clockadile Dundee;7235683*
> That tank will be turning left.


I'm sorry but you fail. That tank would be turning right. A tank turns towards the slower tread, so it would turn right. World class trolling, right there







.


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## almighty15

This is a simplified list of what goes on when you play a game.

- The CPU sends draw calls to the graphics driver, These draw calls could be anything from rendering a little tree to a mega battle with loads of explosions.

- The graphics driver then turns that into a scheduled rendering list and feeds it to the graphics card.

- The graphics card renders the list sent to it by the graphics driver.

Now as we all know CPU have varying amount of power, And we also know that games don't just consist of graphics.

There's sound, Physics, artificial intelligence and general game management code all running and requiring processing at the same time that these graphics draw calls are being processed.

Now if a large part of a CPU's resources are being consumed by sound, physics or artificial intelligence then there's not a lot of spare CPU processing cycles left over for processing the draw calls.

Now if you have a relatively weak graphics card this isn't a problem as the CPU could easily keep the graphics driver and thus, The graphics card fed with rendering information.

Now throw a high end graphics card and you're in trouble, With the CPU using it's processing power on other aspects of the game the monster GPU is stood idle waiting for rendering information.

And that is a CPU bottleneck.

It's also the reason why games that do support quad cores always benefit as there's more cores and CPU cycles to generate these draw calls while other cores handle other aspects of the game.


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## XiDillon

Quote:


> Originally Posted by *Alanhunt123;12560271*
> I'm sorry but you fail. That tank would be turning right. A tank turns towards the slower tread, so it would turn right. World class trolling, right there
> 
> 
> 
> 
> 
> 
> 
> .


Didnt say which way the wheels were rolling atop of the tread tho either....so it could still claim to be turning either way









^^^^^^^
Military Class Trolling right thar!


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## rdrdrdrd

ahh gravediggers...


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## Belial

I think my Athlon II X4 3.5ghz is bottlenecking my GTX 460 (1280x768). When I run MSI Kombustor stability/testing utility, the FPS is about 26fps - when I overclock the GTX 460 to ridiculously dangerous levels, the FPS is still 26fps.

On the plus side, I can play every game on max, just fine. It's kind of annoying there is no point in overclocking my GPU (not to mention my CPU couldn't really overclock past 3.5 no matter the voltage ;/ )


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## eugene12345

Too much wizardry in this thread. NERF NECROMANCERS BLIZZARD! AGFAGDGASDGASD


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## Belial

So am I right in believing my CPU is bottlenecking my GPU? (3.5ghz athlon ii x4, gtx460) My fps didn't change when overclockign and at stock with the benchmark test in furmark/kombustor (same thing actually) - 25fps at 1280x768 with xtreme burn and post processing.


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## Belial

^up?


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## pursuinginsanity

Quote:


> Originally Posted by *Belial;12741267*
> So am I right in believing my CPU is bottlenecking my GPU? (3.5ghz athlon ii x4, gtx460) My fps didn't change when overclockign and at stock with the benchmark test in furmark/kombustor (same thing actually) - 25fps at 1280x768 with xtreme burn and post processing.


At 720p, yeah, you're going to be CPU limited in most modern games. Unless you're experiencing stuttery game play, this is not important.

Next time, start your own thread instead of continuing this necro.

Mods, can someone close this? It's from 2008..


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## Belial

^ it was bumped by someone else and no i dont get stuttery game play :O


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## paulerxx

Let's say your CPU can reach "50 x" and your GPU can reach "100 x".

Because your CPU can only reach 50 x, your GPU will only reach 50 x. So in this case you usually just jack up the AA/AF so they both run at 50 x..In the end, they'll be running at 50 anyways soo why not have some extra eye candy?
















EDIT: Face to palm..Just looked at the original post's date. CLOSE/


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## Belial

^ right but instead of making a new thread, I'm hijacking this thread:
Quote:


> So am I right in believing my CPU is bottlenecking my GPU? (3.5ghz athlon ii x4, gtx460) My fps didn't change when overclockign and at stock with the benchmark test in furmark/kombustor (same thing actually) - 25fps at 1280x768 with xtreme burn and post processing.


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## Belial

soooo it sounds right an athlon X4 @ 3.5 ghz 2.5ghzNB would bottleneck a stock 460?


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## cokker

At 1280x768 your CPU is doing most of the work, either crank up the AA/AF and enjoy the pretty or get a higher resolution monitor.

If you wanna talk silly, you could say your monitor is a bottlenecking your graphics card as it's not allowing it to stretch its legs.

At 1680x1050 I can play Metro2033 on high with DX11 in the high 40's or very high with DX10 in the high 80's (Inside). My CPU is only working a little faster than yours and it seems like a good match in most games.

TL;DR, Get a higher resolution monitor and your graphics card will start pulling its weight.

Now let this tread die, thank you.


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## namelessnick1

terribly old thread? yes

But I really enjoyed reading it, feel like I learned a bit

Thanks to you who bumped ancient thread


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## SC2pro

games depend on the cpu and gpu. if ur gpu is fast and ur cpu is slow/old you wont get a really good performance because the game needs more speed from the cpu. in games, cpus have a different role than gpus thats y it will hold ur graphics card behind in terms of performance.


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## robwadeson

why are we even discussing this? It's pretty obvious that if your cpu is slow then the whole experience would be slow no matter of other components...


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## AtheistDane

Know it is kind of a newbish question but will I experience a lot of bottlenecking pairing a Core2 Quad Q9300 (2.5 GHz) with a Palit 560 Ti Sonic (1GB)?

Hope this is not a too stupid question to answer..

Regards,
AtheistDane


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## brettjv

Quote:


> Originally Posted by *AtheistDane;14151920*
> Know it is kind of a newbish question but will I experience a lot of bottlenecking pairing a Core2 Quad Q9300 (2.5 GHz) with a Palit 560 Ti Sonic (1GB)?
> 
> Hope this is not a too stupid question to answer..
> 
> Regards,
> AtheistDane


It depends on what test you run (i.e. what game/bench), and what settings you run that test at (res, aa, other IQ settings). It also depends on what your own personal definition of 'a bottleneck' is.

I personally stick by the literal definition of the term ... if I get 100fps on game X at 1920x1200 on Very High, with 4xAA, with my CPU at 3.0GHz, then I OC my proc up to 4.0GHz, and end up getting 105fps on game X at the exact same settings ... then I had a CPU bottleneck, in game X, at those settings, at 3.0GHz. And I might still at 4.0GHz, I can't really know unless I OC it even more and compare scores.

Now, that is using the actual definition of the term. Yes, it's a very slight CPU BN, and it's an irrelevant one, and it ONLY applies to that game, at those settings ... but it technically still IS one.

By MY definition, yes, there will definitely be some bottlenecking on certain games/benches with the setup you propose. On rare occasions, the BN might actually reach the status of 'a lot'.

So ... what is YOUR definition of the term, and what games do you generally play, and at what resolution, and what IQ settings?

Basically the harder you make the game to run graphically, by increasing resolution and image quality, the lower the FPS will be, due to your GPU having to work harder. This, in turn, lowers the probability that your CPU will be the 'limiting factor' to performance, because less FPS = less data that the CPU has to process over a given period of time.


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## phosedy

I'm going to buy a new gfx-card, but i don't know wich one to choose yet. It's either Ati 5770 or 6850 (green edition without the extra power-connector). Since i have a Shuttle im going to buy a single-slot type. My CPU is Intel Dual Core E5700 3.0 GHz. Will my CPU bottleneck both the 6850? Should i go for the 5770 instead?

Thanks in advance.


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## Chris13002

I bottleneck my processor at 4ghz, when I play the new Deus Ex: HR maxed out... Both my GPU's usage reach up to 82% and thats it.
When I play more stressful games like Crysis or 3dMark, It will jump to 99%...

Like stated above, it all depends on the application, and which it will utilize more, and keeping up with the latest games; you will NOT want a Pentium 4 with a Fermi GPU...


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