AMD's CrossFireX: Tri & Quad GPU Preview

DJ_PAPA

Power Member
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Final Words

We have to give AMD credit, there was no cherry picking of titles for this preview - for the most part, the benchmarks AMD itself selected showed no real need for 4-way CrossFireX over 3-way. We do appreciate the honesty, but it's clear that the world just isn't ready for a quad-GPU solution.

Due to the state of AMD's driver optimizations DX10 games currently only scale well to 3 GPUs and not much beyond (Crysis/Bioshock), while DX9 games will generally scale better all the way up to 4 GPUs. We expected the opposite to be true but AMD provided us with technical insight as to why it is the case:

"The biggest issue is DX10 has a lot more opportunities for persistent resources (resources rendered or updated in one frame and then read in subsequent frames). In DX9 we only had to handle texture render targets, which we have a good handle on in the DX10 driver. In addition to texture render targets DX10 allows an application to render to IBs and VBs using stream out from the GS or as a traditional render target. An application can also update any resource with a copy blt operation, but in DX9 copy blt operations were restricted to offscreen plains and render targets. This additional flexibility makes it harder to maximize performance without impacting quality.

Another area that creates issues is constant buffers, which is new for DX10. Some applications update dynamic constant buffers every frame while other apps update them less frequently. So again we have to find the right balance that generally works for quality without impacting performance.

We are also seeing new software bottlenecks in DX10 that we continue to work through. These software bottlenecks are sometimes caused by interactions with the OS and the Vista driver model that did not exist for DX9, most likely due to the limited feature set. Software bottlenecks impact our multi-GPU performance more than single GPU and can be a contributing factor to limited scaling.

We’re continuing to push hard to find the right solution to each challenge and boost performance and scalability wherever we can. As you can see, there are a lot of things that factor in."

From AMD's explanation it sounds like there's still a lot of work to be done on the CrossFireX driver. While we can expect to see its public debut in March, it seems like it'll be a while before we're anywhere close to ideal scaling. We've found ourselves in this position with many-GPU designs in the past, at least the players are taking things a bit more seriously this time around.

http://www.anandtech.com/video/showdoc.aspx?i=3232&p=1

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PCGH: exclusive benchmarks from AMDs Quad Crossfire
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http://www.pcgameshardware.de/aid,6...xclusive_benchmarks_from_AMDs_Quad_Crossfire/

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CrossFireX preview
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Summary
We've seen first-hand that CrossFireX, in its three- and four-GPU incarnation, works well enough in DX9 titles run at ultra-high resolutions and image-quality settings.

A single-GPU Radeon HD 3870 is no slouch but performance can be up to 3x better with dual Radeon HD 3870 X2s. That will only really matter if you're playing fast-paced games and want all the eye candy turned on to maximum, however.

Scaling, though, is comparatively limited with the DX10 API and Crysis - which is the most talked-about game of 2007 - gains are virtually non-existent at high resolutions.

Given what we've seen thus far, the optimum combination, assuming the underlying hardware is in place, appears to be a three-GPU graphics sub-system run at 1,920x1,200 and above. NVIDIA, we note, already has three-way SLI for its GeForce 8800 GTX and Ultra SKUs.

It's difficult to give firm buying advice with such a nascent technology. What we can say for now is that CrossFireX opens up new, flexible avenues for potential upgrades in the HD 3800-series family.

However, we reckon that the majority of popular gaming titles will need to scale to 3x before four-GPU operation becomes compelling enough to invest in.

Further analysis will be presented as we review the CrossFireX driver before its launch with the CATALYST 8.3 drivers.
http://www.hexus.net/content/item.php?item=11874&page=1
 
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Pois, só "vale a pena" até 3.

4 graficas ainda não compensa.

Acho que é preciso muita largura de banda para 4 graficas. Já começa a atrofiar....
 
AMD Quad-CrossFire - CrossFireX Performance Preview

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Nesta review o Crysis ta interessante:

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Ah, the true nexus of why multi-GPU gaming is so important to us: Crysis! At first the performance scaling at 1024x768 seems a bit unnerving since we are only getting an average frame rate of 40.3 with four GPUs pumping on the game - however that is a noticeable increase over both the single HD 3870 and the dual-GPU HD 3870 X2. Looking at 1280x1024 though, the move from three GPUs to four GPUs is still not impressive even though the minimum frame rate sees a HUGE jump of 67% or so. The performance of three and four GPUs is still impressive for this title, unfortunately, as we are getting very playable rates here for nearly the first time.
http://pcper.com/article.php?aid=523&type=expert&pid=1

Quem possua uma HD 3870 pode fazer crossfire com uma HD 3870X2 e ter um scalling muito bom em Tri-crossfire.
E segundo a equipa de drivers da AMD em DX_9 é relativamente facil por um sistema full-working, enquanto que em DX_10 se torna tudo muito mais complicado.
 
PCGH: exclusive benchmarks from AMDs Quad Crossfire

The benchmarks were done by our graphics card editor Daniel Waadt in AMD's offices. Although we had some AMD bodyguards with us, we were totally free in deciding with benchmarks and which settings we would like to test. To measure the performance of four chips - you might remember that the HD 3870 X2 has two GPUs - we used several programs like Crysis in DX10, UT3, Call of Duty 4 and 3DMark 06.

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VIDEO






Full English article:
http://www.pcgameshardware.de/aid,6...xclusive_benchmarks_from_AMDs_Quad_Crossfire/

Direct link to the image gallery:
http://www.pcgameshardware.de/?menu=browser&article_id=633062&image_id=778562

("nächstes Bild" means "next picture", click the picture to enlarge it)

The benchmarks were done at AMD with a system they provided, so please don't blame us for using a slow CPU, etc.



xtremesystems




cumps
 
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Deixem os drivers genéricos sair, onde não seja preciso fazer truques ou optimizações para os jogos ganharem + qualidade , e eu compro.
A configuração tem de ser invisivel para os jogos para esta tecnologia poder avançar.
e tem de correr os jogos antigos como deve ser , coisa que Nvidia e Ati têm esquecido.
nos entretantos, fico-me por uma placa única (que é mais que suficiente).
Deixem chegar os multi-GPU , multi-cpu tudo integrado como deve ser.
 
Os ganhos são ainda ridiculos para a despesa que é.

Se já uma X2 enfrenta problemas, duas destas é showoff, pouco mais.

Em tri-crossfire os ganhos são muito interessantes. Isto é juntar uma HD 3870 + HD 3870X2. E não te esqueças que foi um teste com drivers ainda um pouco verdes.

Se somares o preço de uma HD 3870 + HD 3870X2 da-te 380 + 180 = 560 euros o que nem é assim muito caro.
Mas claro isto é so para quem pode. (1% do mercado se tanto)
 
Uma hd3870x2 mais uma hd3870 é preciso uma fonte de pelo menos quantos watts?



abraço,

I have put an extra Enermax Liberty 400W PSU and just connected the VidCard.
Switching the PSU for the GPU on but not the PC, the wattmeter says about 8W, so this is ground zero.

Idling Windows XP:
35,5W - 8W = 27,5W

Benchmark Crysis GPU:
MAX: 161W - 8W = 154W
AVG: 140W - 8W = 132W

For the power consumption under load i found something funny.
The power consumption raises when the fan is also running faster.

+

pc.gif


= Fonte de 600W SLI(Yeah, I know) ready deve chegar.
 
Ja podiam pensar nos GPU dual core.

Penso q a ATI tem mais possibilidade disso q a Nvidia.

O pior é o consumo, um PC com 4 graficas e OC e o CPU em OC da para servir de aquecedor central.
 
Ja podiam pensar nos GPU dual core.

Penso q a ATI tem mais possibilidade disso q a Nvidia.

O pior é o consumo, um PC com 4 graficas e OC e o CPU em OC da para servir de aquecedor central.

não compensa.
o resultado da duplicação do nº de shaders num unico GPU, é em principio mais vantajosa, que simplesmente por 2 GPUs em 1, até porque, como tem sido habitual nestes sitemas crossfire e SLI, o incremento de performance, pode ser decepcionante, e fica habitualmente abaixo do que seria de esperar.
 
Na semana que vem vou cá ter uma HD3850 512mb de um amigo para emparelhar com a minha x2.. se vir k akilo dá algum rendimento.. especialmente no crysis.. então pondero mesmo em comprar uma HD3870 single para o tri-crossfire, senão.. axo k mais vale mesmo esperar pelo próximo single card valente.. tipo, substituto da 88gtx, mas que seja digno de ser sucessora dela.

Vi montes de testes e axei k corria perfeitamente o crysis em high a 1920x1200 com a x2, 3G de ram e o cpu a 3.8 e afinal não é bem assim.. ou seja.. eu kero ver se isto funciona mesmo é com os meus olhos.

E quanto ás fontes há muito mito de volta disso... uma fonte minimamente boa de 500-600w mama tudo.. é claro que extreme OC pede "detalhes", mas fontes com uma boa amperagem nos 12v e cerca de 500w aguentam perfeitamente grandes cargas.

A melhor forma de ver se ela se está a aguentar muito bem ou mal é a quantidade de calor emanada pela mesma.. se for estrondosa é claro k convem comprar uma mais potente.
 
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