SLI vs. CrossFire, Part 1 – mid-range multi-GPU scaling & value
Left 4 Dead
Left 4 Dead (L4D) is a 2008 co-op first-person shooter that was developed by Turtle Rock Studios and purchased by Valve Corporation during its development. Left 4 Dead uses Valve’s proprietary Source engine . L4D is set in the aftermath of a worldwide pandemic which pits its four protagonists against hordes of the infected zombies. There are four game modes: a single-player mode in which your allies are controlled by AI; a four-player, co-op campaign mode; an eight-player online versus mode; and a four-player survival mode. In all modes, an artificial intelligence (AI), dubbed the “Director”, controls pacing and spawns, to create a more dynamic experience with increased replay value. It is best as a multiplayer game with humans.
There is no built-in benchmark, so we created our own custom time demo which is very repeatable. The game is updated regularly by Steam and we chose the highest detail settings and 8xAA. We will save our comments until after we present both charts. First we test at 2560×1600 resolution:
On to our next chart at 1920×1200:
All of our video cards can play this game fully maxed out plus 8xAA, except for the GTS 450 at 2560×1600 which then benefits sufficiently to be playable after being SLI’d. The GTX 580 stands out although the HD 6870 comes pretty close at 2560×1600 and yet they are still beaten by every flavor of each tested SLI and CrossFire combination except for GTS 450 SLI.
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.