SLI Performance Testing
For our quick little check of SLI performance, we connected our reference and Galaxy GTX 670 cards together, using the same 301.34 driver and compared them to a pair of Radeon HD 7950 3GB cards running in CrossFire with Catalyst 12.4.
Sorry for the lame photo here, but last minute camera phone shots will do that do you. Our SLI and CrossFire comparison below only looks at the bar graph versions of our 1920×1080 results as they appeared to be right in with scaling at 2560×1600 as well.
If the HD 7950 was behind in single card testing it only makes sense that it would fall behind in multi-GPU testing as well, which it does. In general, SLI seems to be more compatible than CrossFire with issues arising in our 7950s configuration with Skyrim, Batman: Arkham City and Deus Ex: Human Revolution. For NVIDIA though, if we only take Skyrim out of the equation, the GTX 670 sees an average scaling factor of 1.71x by adding a second card in our testing.
The synthetic benchmarks show a similar story though with higher scaling – both the GTX 670 and Radeon HD 7950 see nearly perfect scaling in 3DMark11 on the Extreme preset. At the Extreme tessellation setting on Heaven we see 94% and 97% scaling respectively as well.