# HTPC Motherboard question? 790GX vs. 785G



## EvilGenius007

Have you seen details on which video chipsets the 785G will be able to Hybrid CrossfireX with? If you can go 785G/4550 then it may be worth the wait. However, if you're limited to the 4350 it's not: you'll probably get about the same results with a stand-alone 4550 or GeForce 9400 (available in passive, single-slot half-height) or a 790GX/3450 hybrid.

If you're looking to do a full-height build, and/or are willing to lose a slot to a double-wide passive heatsink, you have still more options.

You should also factor in probable/possible delays in 785G becoming readily available and expect to pay a premium for the new tech that isn't fully justified based on how it performs. Your best performance per dollar will be the 790GX/3450 hybrid combo, and should beat a stand-alone 785G in both performance and cost (at least for the first month or so the 785G is on the shelves) and only lose slightly on heat & power consumption.

785G Advantages:
Potentially slightly more powerful hybrid crossfire cap
Potentially slightly lower power consumption in stand-alone than comparable 790GX hybrid set-up

790GX Advantages:
Known capabilities
On shelves now
Good price/performance ratio due to low/moderate demand (niche market vs. 780G & 790FX chips)


----------



## Ric2L

Quote:


Originally Posted by *EvilGenius007* 
Have you seen details on which video chipsets the 785G will be able to Hybrid CrossfireX with? If you can go 785G/4550 then it may be worth the wait.

I can't seem to find anything on the Hybrid CrossfireX anywhere, but there is a thread on AVSforums by Renethx that has some pretty good info about the Gigabyte 785 boards (http://www.avsforum.com/avs-vb/showthread.php?t=1163214).

These boards have alot of nice options for a HTPC build, 80 stream processors?, twice those of HD 3200 (unconfirmed)
DirectX 10.1 support
2nd generation Unified Video Decoder (UVD 2)
Full hardware decode acceleration of H.264/VC-1/MPEG-2 (full hardware decode acceleration of MPEG-2 is not supported in HD 3200?)
Hardware decode acceleration of a secondary video stream (Picture-in-Picture) (10-20% CPU usage decrease)
Improved ATI Avivo Video Post Processor
Enhanced DVD up-conversion to HD
Automatic dynamic contrast adjustment
Multichannel LPCM over HDMI (no PAP, no HD audio bitstreaming, of course)
Southbridge SB710

ACC (Advanced Clock Calibration) support

I may have to wait a week or two to read a full review of a production board. anyway something to think about.


----------



## Enigma8750

Basically what I'm seeing here's is the AMD 880 chipset yet renamed to 785G. The only real new difference is that a new graphics core now is used in the 785 series. The new IGP is dubbed Radeon HD4200, while the 780G's IGP was named Radeon HD3200. You should start seeing 785-equipped motherboards quite soon. The 3200 on a 3D Mark 06 will get you about 1500 to 1800 score. The 4200 with 128 mb of DDr3 1333 ram will probably get about 3300 on the 3D Mark 06. Not bad for watching Blu-Ray and basic HTPC Applications. I currently have a 4550 512 board in my HTPC and I love it.


----------



## EvilGenius007

I'm not disputing that the 785G is a great chip, and I'm pretty certain that when they finally become available motherboards based on the chip will be a welcome addition to the HTPC market.

I'm just saying that if you're building in the next 4-6 weeks I'd choose a 790GX/3450 hybrid for about the same cost, similar capabilities and no wait. The only caveat being if you're going to be using the video card's HDMI audio to feed a 7.1 surround system. Since it looks like Ric2L is planning to spend $150 on a sound card anyways, I don't think that's an issue here.

If you can wait 6-12 weeks for the official product release & prices to fall off the "novelty" range, or you have an AM3 chip and some DDR3 RAM sitting around already that you can use to offset the cost difference, then the 785G is probably a better fit.


----------



## Ric2L

New question, if one was to go with a dedicated sound card (Asus Xonar 1.3 slim) and a dedicated video card (HD 4670, HD 4770) would it be best to go with the 790GX boards or would there be a better choice in the AM3/DDR3 crowd?


----------



## alwaysAMD

The onboard sound is not half bad in my opinion, and a HD4670 should be more than enough for light gaming.


----------



## EvilGenius007

A 790X board might be cheaper, and a 790FX board would have more PCI-x16 slots and possibly other features you wouldn't really need in a HTPC but might want somewhere down the line if you re-tasked this system for non-HTPC purposes.


----------



## EvilGenius007

FWIW, the Anandtech announcement regarding the official 785G release states that Hybrid Crossfire support remains limited to HD3450/3470 GPUs.







Hopefully driver revisions down the line can rectify that situation, but in the meantime it's "wait and see".

Also, I was overly pessimistic both regarding the pricepoint & date of actual 785G availability. I have a feeling the "accidental" early sale of Gigabyte boards may have influenced the date, and I can only say I'm pleasantly surprised the prices are in the $90 range to begin with.


----------



## Ric2L

Newegg has 6 785G boards listed right now (http://www.newegg.com/Product/Produc...ame=AMD%20785G) Prices between $79.99 and $99.99.

I'm really liking that Asus EVO board. Just might have to pull the trigger on it.


----------



## Ric2L

Well, now it seems that the 785G chipset does NOT SUPPORT 8 CHANNEL LPCM over HDMI. See AnandTech article (http://search.myway.com/search/redir...iQ%3D%3D&ct=AR)

So now I guess if I want 7.1 LPCM to my receiver its with a dedicated audio card, or nvidia 9400 chipset, or a G45 board???


----------



## EvilGenius007

Avoid G45 if you want to do full screen playback of Flash video (Hulu). Apparently it stutters even under most reasonable dual cores. I thought you were considering the Xonar HDAV Slim anyways? It won't matter what sound your video signal outputs with that card. The Xonar will discard it, keep the video, and add it's own bitstreamed audio.

EDIT: Any HD4xxx series discrete card will also do 8 channel LPCM, as will (I believe) any 9xxx series and 2xx series nVidia card, as long as there's an S/PDIF out header on the mobo or sound card.

Also, you may be able to directly connect the integrated the sound on the mobo to your receiver by S/PDIF optical or coaxial and get 8 channel sound. Not sure if it will be LPCM or not though, or of the loss of quality will be discernible anyways.


----------



## Ric2L

Quote:


Originally Posted by *EvilGenius007* 
I thought you were considering the Xonar HDAV Slim anyways?

I was, but if the 785G did 8 channel over HDMI, I figured I wouldent need the Xonar card. But.... now it looks like its back on my shopping list. I have to wait till I get back from vacation befor I buy, so that gives me till after labor day to figure out which board to go with. I'm still leaning toward the 785g with a Xonar card. but for now I'm open to other/better options???


----------



## EvilGenius007

One of the articles I read about the 785G said it will be Hybrid CrossfireX compatible with a yet-to-be-released line of ATI graphics cards. Since it's likely they'll have 7.1 sound I'd hold off on purchasing a $150 sound card and either buy an HD4350 (~$30) or see how the integrated audio sounds before making any purchasing decisions.


----------

