There are really no noticeable differences between the SLI and single GPU setup at this low a resolution. There is simply not enough GPU dependency for us to see performance improvements yet.
Once we turn on the 4xAA setting on Doom 3 at 1280×1024 resolution, we can already see the scaling of the SLI configuration. The dual GPU setup barely comes down from the 60 fps max on the Doom 3 engine while the single GPU setup drops below 30 fps. The difference in the average FPS scores doesn’t give the SLI enough of an edge here.
Without the AA, the SLI isn’t really utilized, but with 4xAA again we see the shining example of SLI performance. Here we see a 28% performance improvement in the average frame rate and a 100% improvement on the minimum FPS. In fact, during the entire 2nd half of our playing, the average on the single card (red line) is under the 40 FPS mark while the dual card (blue line) setup remains easily above 50.