SLI vs. CrossFire, Part 1 – mid-range multi-GPU scaling & value
Enemy Territory: Quake Wars
Enemy Territory: Quake Wars is an objective-driven, class-based first person shooter set in the Quake universe. It was developed by id Software and Splash Damage and published by Activision. Quake Wars pits the combined human armies of the Global Defense Force against the technologically superior Strogg, an alien race who has come to earth to use humans for spare parts and food. It allows you to play a part, probably best as an online multi-player experience, in the battles waged around the world in mankind’s desperate war to survive.
Quake Wars is an OpenGL game based on id’s Doom3 game engine with the addition of their MegaTexture technology. It also supports some of the latest 3D effects seen in today’s games, including soft particles, although it is somewhat dated and less demanding on video cards than many DX10 games. id’s MegaTexture technology is designed to provide very large maps without having to reuse the same textures over and over again.
For our benchmark we chose the flyby, Salvage Demo. It is one of the most graphically demanding of all the flybys and it is very repeatable and reliable in its results. It is fairly close to what you will experience in-game. All of our settings are set to ‘maximum’ and we also apply 4xAA or 8xAA plus 16xAF in game. First we test at 2560×1600 resolution with all settings fully maxed in-game plus 4xAA/16xAF:
Let’s crank up the anti-aliasing from 4x to 8x while we test at 1920×1200 resolution.
Here we see the GTS 450 is unable to play this game even in SLI as the minimums do not gain much and it is still a chugging slideshow at our chosen resolutions with highest details. On the other hand, although neither the GTX 460 nor GTX 560 gain much in the minimums, they are able to benefit in the averages to give a more fluid experience since they are already strong enough performers as single cards. SLI simply does not scale well in this game while CrossFire scales fairly well.
I’m not 100% certain, but to analyze microstuttering, place a check in the box next to “Frametimes” in Fraps. Then when you press the hotkey, it will create a log file with a timestamp when each single frame was outputted. Only a few seconds is enough to make the log file really, really long. Then take a portion out of the log file and make a chart out of it, that measures the time between each timestamp, to see if the frames are consistent with each other in similar intervals, or if every other frame is too close to the other one.
If a game runs at say, 45fps with your SLI or CF setup, but feels more like 23-30fps, then definitely analyze this with FRAPS.
Great review so far.
How do the numbers change, if at all, if Split Frame Rendering is used instead of Alternate Frame Rendering?
The last time I used SLI was with my Voodoo2 3000s. It was a gigantic waste of $200, in 1996 dollars.
If SFR eliminates micro-stutter without too much of a performance penalty I might have to try SLI again.
why don’t they add BF:BC2?
and also 6950 n 6970 crossfire?
Concerning the microstutter, frames time (using that fraps option) is supposed to fluctuate more erratically on crossfire/sli than what it would be on a single card. I think instead of testing a moving scene, it would make more sense to test it on a completely still scene for a few seconds and see how they compare in the excel output file. You don’t want a moving scene because then you won’t be able to differentiate between the erracticness you would get from a moving scene and the erraticness you would get from microstutter.
Another interest option would be to downclock a sli/crossfire setup to a point where it matches the average framerate of the single card. This way you could could see if the multi-gpu setup looks choppier than a single card despite having the same average frame rate.
Excellent work! At the end, simple recommendations would have been nice. =)
Please include Civilization 5 if possible the next time you benchmark.
It is an important game which will test the tesselation feature and its scaling ability in multi-gpu configurations.
Civilization 5 has been added to my benching suite along with DiRT 3 and Total War, Shogun 2.
You’ve done a great job of benchmarking gaming performance, but including charts with FPS vs $$, and $$ vs wattage would be much more useful.
The wattage (both idle and load) figures can be especially important, as some of these cards can easily draw more juice than all but the most powerful (and expensive) power supplies can provide — and that definitely factors into the cost analysis.