GTX460 SLI Surround Benchmarks
I will provide results obtained first with an SLI setup of two 1GB cards, followed by results obtained from an SLI setup of two 2GB cards, for each game tested. Some discussion will occur at each stage, with a general discussion and overall conclusion at the end of the review.
Games will be quickly detailed and their Surround support quantified by a four step scale; excellent, good, poor or abysmal.Aliens vs. Predator (2010)Genre: First Person ShooterSurround Support: Excellent
Aliens vs. Predator was benched with the following settings: DirectX 11, 16xAF, High Shadow Quality, SSAO On, Hardware Tesselation enabled, Advanced Shadow Sampling enabled. Texture quality, resolution and antialiasing were varied, although only the results from 'Very High' texture quality are shown here. AvP is a demanding next-generation title which takes advantage of DirectX 11 capable hardware such as the GTX460. I am not very far in this game, so used the downloadable benchmark which in analysis appeared to give similar results to the numbers I have been seeing when actually playing the game.
Figure 3: Aliens vs. Predator results working with SLI 1GB GTX460s.
With a pair of 1GB GTX460s in Surround, it is obvious that Aliens vs. Predator is barely able to keep up at Surround resolutions, and is absolutely impossible with Anti-Aliasing applied at a triplescreen res. If details are dropped to High, oddly framerate decreases further (data not shown).
Figure 4: Aliens vs. Predator results working with SLI 2GB GTX460s.
Once a pair of 2GB cards are in use, it is a different story. AvP is just playable with a minimum framerate of 22fps at a bezel corrected resolution of 6064x1200. Those playing at 5760x1080 (or lower, with WSXGA+ panels) should be able to achieve more than playable framerates in AvP. The increased VRAM has the most marked effect of an increase in minimum framerate, even in scenarios where the game is already performing acceptably with 1GB.
Figure 4: VRAM usage at different resolutions in Aliens vs. Predator.
Note that at 6064x1200 4xAA, even the 2GB card appears to run into a VRAM limit, albeit a minor one. This demonstrates very well that a 1GB card does not have enough VRAM to cope with the demands of a DX11 title with all the bells and whistles added. The low readings on the 1GB cards for 5760x1200 4xAA and 6064x1200 4xAA can be attributed to the game attempting to page VRAM data to system RAM, and failing to fill the VRAM as a result. When Alt-Tab was used to move out of the benchmark at one point (during a run where no data was collected) Task Manager reported no free system RAM (of 6GB), presumably it was further utilising the pagefile on the hard drive.
-----DiRT 2Genre: Racing
Surround Support: Excellent
All settings at maximum, including Post Processing at 'High'. Resolution and AA varied. I quite like DiRT2, so decided to bench based on a player-controlled race: Battersea, three laps, 7 opponents, starting at the back of the grid.
Figure 5: DiRT 2 results working with SLI 1GB GTX460s.
DiRT2 appears to have a built-in framerate cap at 60fps. I made sure I disabled Vsync both in game and in nVidia Control Panel, yet I never saw more than 60fps (even tried 1024x768 to make sure...) as with AvP, it is evident that the 1GB cards cannot cope with Surround at maximum settings. However, I was able to play DiRT 2 with Post Processing on Medium and 0xAA at 6064x1200 on 1GB cards and maintain a minimum of 40fps (data not shown). If I have enough time over the next few weeks, I will go back and slowly step all the settings up from minimum one at a time to show where this VRAM bottleneck occurs. DiRT 2 does appear to suffer from severe performance decreases with bezel correction enabled on 1GB cards. While I would not call 5760x1200 playable, the 7fps minimum occurred in the pre-race camera panning â€“ during racing itself, FPS never dropped to a point where it was noticeably jerky, thus I presume that it was at least 20fps during racing at all times.
Figure 6: DiRT 2 results working with SLI 2GB GTX460s.
With 2GB cards, framerates pick up exceptionally. In fact, I never intended to test 6064x1200 8xAA, but the framerate at 4xAA was still good, so I decided to try it. This resulted in a very interesting result: average fps was easily playable, but during the pre-race camera pan fps was single digits and after I crossed the finish line framerate actually reported 0fps for a second.
Figure 7: VRAM usage at different resolutions in DiRT 2.
Looking at the VRAM usage figures, hopefully it becomes evident why 6064x1200 8xAA hit such a performance brick wall: even on a card with 2GB of VRAM, DiRT 2 at this resolution and settings fills it and wants more. Those final few MB of 2048 are needed for each rendered frame â€“ at 6064x1200 each frame displayed takes up 27.76MB in the graphics card VRAM. Again it is interesting to see that the 1GB cards fail to fill the VRAM at extreme settings before choosing to use system RAM instead.