Doom 3 with 4xAA
id Software Doom 3 with 4xAA

Notes
Understanding that anyone with an SLI setup would want to play games with much more detail enabled, we started our tests at 1024x768 with 4xAA as a baseline. And even then, the 3D1 posts impressive scores that are clearly very playable. It offers about 58 percent more performance compared to just a single GeForce 6600 GT card, but the GeForce 6800 GT is still about 12 percent faster at 1024x768.
As the resolution increases, you can see the 3D1 lose the ability to deliver fluid gameplay, while the 6800 GT and 6800 Ultra are still pretty capable at 1600x1200. At that point, however, the 3D1 is offering nearly 63 percent more speed than the single GeForce 6600 GT to which it’s being compared.