Unreal Tournament 3 demo
We tested the UT3 demo by playing a deathmatch against some bots and recording frame rates during 60-second gameplay sessions using FRAPS. This method has the advantage of duplicating real gameplay, but it comes at the expense of precise repeatability. We believe five sample sessions are sufficient to get reasonably consistent and trustworthy results. In addition to average frame rates, we've included the low frames rates, because those tend to reflect the user experience in performance-critical situations. In order to diminish the effect of outliers, we've reported the median of the five low frame rates we encountered.

Because the Unreal engine doesn't support multisampled antialiasing, we tested without AA. Instead, we just cranked up the resolution to 2560x1600 and turned up the demo's quality sliders to the max. I also disabled the demo's frame rate cap before testing.

The picture looks much the same in UT3. The 8800 GTS 512 slots in just between the GeForce 8800 GTX and the overclocked 8800 GT from MSI. The big difference here is the performance of the Radeon HD 3850 CrossFire config, which turns out higher average frame rates than the GTS 512. Unfortunately, though, the HD 3850 turns in a much lower median low FPS number. In fact, CrossFire doesn't appear to help median low frame rates at all on the 3850, which means it's not a huge help to playability in worst-case scenarios. The same is true of SLI on the GTS 512.

Call of Duty 4
This game is about as sweet as they come, and we also tested it manually using FRAPS. We played through a portion of the "Blackout" mission at 1600x1200 with 4X antialiasing and 16X aniso.

Not to sound like a broken record, but I think we're getting a sense that the 8800 GTS 512 is faster than the GTS 640MB and nearly as quick as the big daddy, the 8800 GTX. The MSI 8800 GT OC remains the fly in the ointment, however.

Frustratingly, AMD doesn't appear to have CrossFire working well with CoD4.