1680x1050 Ultra Performance
Using the ultra quality preset at 1680x1050 our 8-player test limited the average frame rates to just over 60fps. Please note that vsync was not turned on and the maximum frame rates did reach over 90 on many of the high-end cards.
At this resolution the GeForce GTX 460 delivered the same gaming experience as the more expensive Radeon HD 5870 and GeForce GTX 480 graphics cards. Neither Crossfire nor SLI provided any advantages in terms of performance. This should rectify once an updated driver is out.
At this resolution using the ultra preset the GeForce 9800 GT was just able to deliver playable performance, playable in the sense that there was no noticeable lag. StarCraft II plays best with a minimum frame rate of 30fps or greater. Beyond that we have older graphics cards such as the Radeon HD 4870 and GeForce GTX 260 which easily delivered playable performance.