A Look At Triple-GPU Performance And Multi-GPU Scaling, Part 1
by Ryan Smith on April 3, 2011 7:00 AM ESTMass Effect 2, Wolfenstein, and Civ V Compute
Mass Effect 2 is a game we figured would be GPU limited by three GPUs, so it’s quite surprising that it’s not. It does look like there’s a limit at around 200fps, but we can’t hit that at 2560 even with three GPUs. You can be quite confident with two or more GPUs however that your framerates will be nothing short of amazing.
For that reason, and because ME2 is a DX9-only game, we also gave it a shot with SSAA on both the AMD and NVIDIA setups at 1920. Surprisingly it’s almost fluid in this test even with one GPU. Move to two GPUs and we’re looking at 86fps – again this is with 4x super sampling going on. I don’t think we’re too far off from being able to super sample a number of games (at least the console ports) with this kind of performance.
Wolfenstein is quite CPU limited even with two GPUs, so we didn’t expect much with three GPUs. In fact the surprising bit wasn’t the performance, it was the fact that AMD’s drivers completely blew a gasket with this game. It runs fine with two GPUs, but with three GPUs it will crash almost immediately after launching it. Short of a BSOD, this is the worst possible failure mode for an AMD setup, as AMD does not provide individual game settings for CF, unlike NVIDIA who allows for the enabling/disabling of SLI on a game-specific basis. As a result the only way to play Wolfenstein if you had a triple-GPU setup is to change CrossFire modes globally, which requires a hardware reconfiguration that takes several seconds and a couple of blank screens.
We only have one OpenGL game in our suite so we can’t isolate this as an AMD OpenGL issue or solely an issue with Wolfenstein. It’s disappointing to see AMD have this problem though.
We don’t normally look at multi-GPU numbers with our Civilization V compute test, but in this case we had the data so we wanted to throw it out there as an example of where SLI/CF and the concept of alternate frame rendering just doesn’t contribute much to a game. Texture decompression needs to happen on each card, so it can’t be divided up as rendering can. As a result additional GPUs reduce NVIDIA’s score, while two GPUs does end up helping AMD some only for a 3rd GPU to bring scores crashing down. None of this scores are worth worrying about – it’s still more than fast enough for the leader scenes the textures are for, but it’s a nice theoretical example.
| Radeon HD 6970 | GeForce GTX 580 | |||||
| GPUs | 1->2 | 2->3 | 1->3 | 1->2 | 2->3 | 1->3 |
| Mass Effect 2 | 180% | 142% | 158% | 195% | 139% | 272% |
| Mass Effect 2 SSAA | 187% | 148% | 280% | 198% | 138% | 284% |
| Wolfenstein | 133% | 0% | 0% | 151% | 96% | 145% |
Since Wolfenstein is so CPU limited, the scaling story out of these games is really about Mass Effect 2. Again dual-GPU scaling is really good, both with MSAA and SSAA; NVIDIA in particular achieves almost perfect scaling. What makes this all the more interesting is that with three GPUs the roles are reversed, scaling is still strong but now it’s AMD achieving almost perfect scaling on Mass Effect 2 with SSAA, which is quite a feat given the uneven scaling of triple-GPU configurations overall. It’s just a shame that AMD doesn’t have a SSAA mode for DX10/DX11 games; if it was anything like their DX9 SSAA mode, it could certainly sell the idea of a triple GPU setup to users looking to completely eliminate all forms of aliasing at any price.
As for Wolfenstein, with two GPUs NVIDIA has the edge, but they also had the lower framerate in the first place. Undoubtedly being CPU limited even with two GPUs, there’s not much to draw from here.
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Sabresiberian - Tuesday, April 5, 2011 - link
I've been thinking for quite awhile that we need something different, and this is the primary reason why - I can't get all I want to install on any ATX mainboard I know of.;)
Sabresiberian - Tuesday, April 5, 2011 - link
I've always thought minimum frame rate is where the focus should be in graphics card tests (when looking at the frame rate performance aspect), instead of the average. It's the minimum frame rate that bothers people or even makes a game unplayable.Thanks!
;)
mapesdhs - Wednesday, April 6, 2011 - link
I hate to say it but with the CPU at only 3.33, the results don't really mean that much. I know
the 920 used can't go higher, but it just seems a bit pointless to do all these tests when the
results can't really be used as the basis for making a purchasing decision because of a very
probably CPU bottleneck. Surely it would have been sensible for an article like this to replace
the 920 with a 950 and redo the oc to 4+. The 950 is good value now aswell. Or even the
entry 6-core.
Re slot spacing, perhaps if one insists on using P67 it can be hard to sort that out, but there
*are* X58 boards which provide what one needs, eg. the Asrock X58 Extreme6 does have
double-slot spacing between each PCIe slot, so 3 dual-slot cards would have a fully empty
slot between each card for better cooling. Do other vendors make a board like this? I couldn't
find one after a quick check on the Gigabyte or ASUS sites. Only down side is with all 3 slots
used the Extreme6 operates slots 2 and 3 at 8x/8x; for many games this isn't an issue (depends
on the game), but I'm sure some would moan nonetheless.
Would be interesting to know how that would compare though, ie. a 4GHz 950 on an Extreme6
for these tests.
Unless I missed it somehow, I'm a tad surprised Gigabyte don't make an X58 board with this type
of slot spacing, or do they?
Ian.
xAlex79 - Thursday, April 14, 2011 - link
I am a bit disapointed Ryan in the way you put your conclusions.At the start of the article you highlight how you are going to look at Trifire and Tri-Sli and compare how it does for the value.
Yet at the end in your conclusion there isnt a single mention or even adjusted scores considering value at all. And that makes Nvidia look alot better than they should. It is as you completely forget that three 580s costs you 1500$ and that three 6970s costs you 900$.
Based on that and the fact YOU stated you would take value into account (And personally I think posting any kind of review without value nowdays is just irresponsible and biased) I am very disapointed with an otherwise very good set of tests.
I also understand that this is labeled "Part 1" and that the value might come into "Part 2" but you should have CLEARLY outlined that in your conclusion were that the case. And given the quality of reviews that we have come to expect from Anantech, the final numbers should ALWAYS include a value perspective.
I will jsut outline that it is poor form and not very professional and that in the end the people you should care about are us, your readers. Not how you look or try to look for hardware manifacturers. If this was a mistake, you should correct it asap. It does not make you look good.
L1qu1d - Friday, April 15, 2011 - link
I wonder why they didn't opt for the 270.51 Drivers and went with 3 month old drivers?Compared to the tested drivers:
GeForce GTX 580:
Up to 516% in Dragon Age 2 (SLI 2560x1600 8xAA/16xAF Very High, SSAO on)
Up to 326% in Dragon Age 2 (1920x1200 8xAA/16xAF Very High, SSAO on)
Up to 11% in Just Cause 2 (1920x1200 8xAA/16xAF, Concrete Jungle)
Up to 11% in Just Cause 2 (SLI 2560x1600 8xAA/16xAF, Concrete Jungle)
Up to 7% in Civilization V (1920x1200 4xAA/16xAF, Max settings)
Up to 6% in Far Cry 2 (SLI 2560x1600 8xAA/16xAF, Max settings)
Up to 5% in Civilization V (SLI 1920x1200 8xAA/16xAF, Max settings)
Up to 5% in Left 4 Dead 2 (1920x1200 noAA/AF, Outdoor)
Up to 5% in Left 4 Dead 2 (SLI 2560x1600 4xAA/16xAF, Outdoor)
Up to 4% in H.A.W.X. 2 (SLI 1920x1200 8xAA/16xAF, Max settings)
Up to 4% in Mafia 2 (SLI 2560x1600 AA on/16xAF, PhysX = High)
Fony - Thursday, April 28, 2011 - link
taking forever for the Eyefinity/Surround testing.vipergod2000 - Thursday, May 5, 2011 - link
The one thing that erks me is that the i7-920 OCed to ~3.3Ghz - causing the scaling of 3 cards being greatly reduced as opposed to other forum users that have 3 or 4 cards in CFX or SLI but with fantastic scaling - but assured with a coupling a i7-2600k at 5ghz minimum or a 980x/990x at 4.6ghz+