3-Way SLI Mystery with Crysis
After our initial benchmark tests of Crysis on Falcon Northwest's 3-way SLI Mach V model, we decided to go back for another round of tests using Nvidia's recently released 169.28 beta driver, which was designed to help improve SLI and 3-way SLI performance in conjunction with Crytek's official Crysis v1.1 patch. And after more than a week of extensive testing, we have some good news and some bad news. The good news is, Crysis is almost playable at a maximum resolution of 2560x1600 with all DirectX 10 settings enabled. The bad news is, you have to disable 3-way SLI to achieve it.
If you're scratching your head right now, well, you're not alone. For some bizarre reason, the 169.28 ForceWare doesn't play nice with a 2560x1600 resolution. In fact, as our results show, disabling 3-way SLI and using just one of the 8800 Ultra GPU's inside the Mach V yielded better frame rates for Crysis than using all three video cards. At first we thought we had reversed the findings accidentally - after all, our tests results for other resolutions such as 1920x1200 using the 169.28 driver were quite impressive and saw no such problems. But we ran the tests again and again over several days (and several game and operating system crashes) and confirmed the results.
We used two sample sections of the game: the "First Light" radar station encounter of the first level and the "Paradise Lost" section of the ice level. Let's start with the "First Light" section; we had all settings at very high with a maximum resolution of 2560x1600 and no anti-aliasing (we also had the Nvidia 3D settings at performance for all tests). Here are the results:
With 3-way SLI enabled, this section of the game was flat out unplayable. Crysis would repeatedly freeze for one to two seconds, even during sections with no heavy action or movement, which suggests the issue isn't related to GPU rendering. According to Fraps, the minimum FPS during this test was 0, while the maximum was 12. Mysteriously, the developer mode FPS results claimed a minimum FPS of 1 and a maximum of 46.
With 3-way SLI disabled, however, the results were much better. The game was playable in spurts though it did suffer from frame rate plummets during heavy action. The minimum FPS, according to Fraps, was 2 while the maximum was 13. Meanwhile, the developer mode showed a range of between 4 and 25 FPS.
We then turned our attention to a more taxing section of the game: the start of the "Paradise Lost" level where the island becomes covered with snow and ice. These tests produced more interesting results.
Both tests delivered the same average FPS. Thus, turning 3-way SLI on or off had absolutely no effect whatsoever on this section of the game. But there was a crucial difference in the actual performance of the game. With one GPU, the ice section yielded a minimum FPS of 4 and a maximum of 12. However, with 3-way SLI enabled, the minimum FPS fell to zero while the maximum FPS jumped to 29, more than twice what the single 8800 Ultra could muster. Again, 3-way SLI proves it can raise frame rates for Crysis. But 3-way SLI giveth, and it also taketh away; the minimum FPS dropped all the way down to zero, with numerous, painful pauses.
We discussed our findings with both Falcon Northwest and Nvidia. Fortunately for Falcon Northwest (and unfortunately for Crysis fans), the issues with the game were not hardware related. According to Nvidia, the problem is exclusive to 2560x1600 resolutions (see next page for more encouraging results at a lower resolution) and is most likely a memory issue. But is it cause by the Crysis 1.1 patch or Nvidia's 169.28 ForceWare? Or both? We don't have an answer on that yet, but Nvidia says it's currently working with Crytek on the issue as well as future optimization fixes.
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