CrossFireX Arrives: First Look at 3 and 4 GPUs in 2 Card Setups
by Derek Wilson on March 7, 2008 12:05 PM EST- Posted in
- GPUs
The Test
This time around, we had the opportunity to compare games of our choosing. We did check to see if there were any real performance improvements up from our preview, but we haven't seen any huge changes. Crysis still only shows a performance improvement with two GPUs, and adding a third or fourth can sometimes even degrade performance. That's unfortunate, considering Crysis remains one of the games best able to bring any current GPU setup to its knees.
We decided to tackle this article from the perspective of two-card performance that enables three or four GPUs. This means using the 3870X2 in combination with the 3870 or another 3870X2. There are quite a few permutations that AMD's CrossFireX makes possible. With the way the industry is moving, it seems we won't be able to avoid further investigation into more-than-two GPU configurations. We will definitely continue to investigate this and will report on any interesting findings, but for now we will use two-card setups in order to avoid any concerns about PCI-E slot bandwidth playing a part in our initial performance numbers.
Our goal is to do two things. First, as in our preview, we want to assess the additional benefit gained from going to three or four GPUs. This is obviously relevant, as we want our readers to know what they are getting for their investment. Second, we want to compare the performance of the 3870 in its multiple configurations to other competing solutions from NVIDIA. This will help us to put the performance in a context of relative value to other single and dual card options.
Our test system is Intel's Skulltrail, as it has been in the recent past for graphics articles. We have moved off the AMD Phenom system and will now be able to better compare relative performance values on the best platform to do so. Here is our test setup:
| Test Setup | |
| CPU | 2x Intel Core 2 Extreme QX9775 @ 3.20GHz |
| Motherboard | Intel D5400XS (Skulltrail) |
| Video Cards | ATI Radeon HD 3870 x2 ATI Radeon HD 3870 NVIDIA GeForce 9600 GT 512MB NVIDIA GeForce 8800 Ultra |
| Video Drivers | Catalyst 8.3 ForceWare 169.28 ForceWare 174.12 (9600 GT only) |
| Hard Drive | Seagate 7200.9 120GB 8MB 7200RPM |
| RAM | 2xMicron 2GB FB-DIMM DDR2-8800 |
| Operating System | Windows Vista Ultimate 64-bit |
Crysis Performance
As one of the most demanding titles currently available, Crysis seems like a great showcase for multi-GPU technologies. We did test performance, but with the current drivers we saw no improvement in performance. However, we also tested prior to the 1.2 patch that just came out on Thursday. We will look at Crysis performance in a future update once we have conducted additional testing.
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DerekWilson - Saturday, March 8, 2008 - link
that is key ... as is what ViRGE said above.in addition, people who want to run 4 GPUs in a system are not going to be the average gamer. this technology does not offer the return on investment anyone with a midrange system would want. people who want to make use of this will also want to eliminate any other bottlenecks to get the most out of it in their systems.
not only does skulltrail help us eliminate bottlenecks and look at the potential of the graphics subsystem, in this case i would even make the argument that the system is a good match for the technology.
Sind - Saturday, March 8, 2008 - link
I agree, I don't think the Skulltrail is doing anyone favours of how they could judge utilising these MGPU solutions in a "average" system that the reader on Anand would be using. X38 seems very popular as is 780i, I really don't think even more then 1% of your traffic would ever utilise the system you used to do this review. I've read the other CrossfireX reviews from around the net, and most had no problems at all, and infact most noted that it worked straight out with no messing around with the lengthy directions that were indicated in the article to get it to work.ViRGE - Saturday, March 8, 2008 - link
Something very, very important to keep in mind is that Skulltrail is the only board out right now that supports Crossfire and SLI. If AT wants to benchmark both technologies without switching the boards and compromising the results, this is the only board they can use.Cookie Monster - Saturday, March 8, 2008 - link
No 8800Ultra or GTX Tri-SLI for comparison?DerekWilson - Saturday, March 8, 2008 - link
we were looking at 2 card configurations here ... i'll check out three and four card configs laterJarredWalton - Saturday, March 8, 2008 - link
Unfortunately, Tri-SLI requires a 780i motherboard. That's fine for Tri-SLI, but CrossFire (and CrossFireX) won't work on 780i AFAIK. I also think Skulltrail may have its own set of issues that prevent things from working optimally - but that's conjecture rather than actual testing. Derek and Anand have Skulltrial; I don't.Slash3 - Saturday, March 8, 2008 - link
...graphs are both using the same image. The Oblivion Performance and 4xAA/16AF Performance line graphs (oblivionscale.png) are just duplicates and link to the same file. :)JarredWalton - Saturday, March 8, 2008 - link
Fixed, thanks.slashbinslashbash - Saturday, March 8, 2008 - link
Graphics really are fairly unique in the computing world in that they are easily parallelized. While we're pretty quickly reaching a point of diminishing returns in number of cores in a general-purpose CPU (8 is more than enough for any current desktop type of usage), the same point has not been reached for graphics. That is why we continue to see increasing numbers of pipelines in individual GPU's, and why we continue to see effective scaling to multiple cards and multiple GPU's per card. As long as there is memory bandwidth to support the GPU power, the GPU looks like it is capable of taking advantage of much more parallelization. I expect 1000+ pipes on a 2-billion-transistor+ GPU by 2011.So, I expect multi-GPU to remain with us, but any high-end multi-GPU setup will always be surpassed by a single-GPU solution within a generation or two.
DerekWilson - Saturday, March 8, 2008 - link
that's not the issue ... graphics is infinitely parallelizeable ...the problems are die size and power.
beyond a certain die size there is huge drop off in the amount of money and IHV can make on their silicon. despite the fact that every chip could have been made larger, we are working with engineers, not scientists -- they have a budget.
multiGPU allows IHVs to improve performance nearly linearly in some cases without the non-linear increase in cost they would see from (nearly) doubling the size of their GPU.
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then there is power. as dies shrink and we can fit more into a smaller space, will GPU makers still be able to make chips as big as R600 was? power density goes way up as die size goes down. power requirements are already crazy and it could get very difficult to properly dissipate the heat from a chips with small enough surface area and huge enough power output ... ...
but speading the heat out over two less powerful cards would help handle that.
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in short, multigpu isn't about performance ... it's about engineering, flexibility and profitability. we could always get better performance improvement from a single GPU if it could be built to match the specs of a multiGPU config.