We tested by setting Quake 4 to high quality, and then changing to the desired resolution with AA off. Here we see the 6800GT drops off noticeably at a resolution higher than 1024X768. The 7800GTX stays North of 60fps at each resolution, and the 7800GT SLI setup is able to pass it by about 10% at 1600X1200. Solo the 7800GT hangs pretty well with the 7800GTX. The X800XL 512MB drops off considerably after 1024X768 and really is not in the same league as the GeForce cards. At least the extra memory allows it to keep up with the X850XT PE which can not hang with the 6800GT. Now lets see how performance fairs when we switch to 4XAA..You can check out the benchmarks over here.
Quake IV: ATI and NVIDIA cards benchmarked

AMDZone continues their look at Quake 4 performance and now they have a full range of cards comparing ATI and Nvidia. The 6800T, 7800GT, 7800GT SLI, and 7800GTX go head to head with the X800XL 512MB and X850XT PE.