At its High quality preset, Aliens vs. Predator displays almost-linear performance scaling as we move from two-way to three-way SLI with our GeForce GTX 660 Tis.
The GeForce GTX 660 Ti hits its performance ceiling at AvP’s highest-quality settings, roughly matching a pair of GeForce GTX 680s at 5760x1080. Higher resolutions might have shown the GeForce GTX 680s leading. However, we would have needed a trio of 27" screens at 7680x1440 or 30" monitors at 7680x1600.
The GeForce GTX 660 Ti’s narrower memory bus appears to be the most likely culprit for the loss of performance leadership at this game's most demanding settings.
Memory capacity, on the other hand, does not appear to be an issue, as the 2 GB stock-clocked GeForce GTX 680 nearly matches its overclocked 4 GB sibling.
SLI appears to hurt performance in F1 2012 at 1920x1080 and High Quality settings. Based on the slight slow-down we see at 5760x1080, in addition to the bottlenecks we identified in Does Memory Performance Bottleneck Your Games?, it's probable that this title is being held back by platform performance.
Only when we increase the graphics demands with Ultra quality settings do we see our different configurations getting hit in different ways.
For example, the GeForce GTX 660 Tis in SLI get hammered pretty hard at 5760x1080. This appears to be due to a combination of its narrower memory bus and lower memory capacity. The 2 GB GeForce GTX 680 also adds perspective, dropping way behind the 4 GB version at 5760x1080, while still beating two GeForce GTX 660 Tis in two-way SLI.