Single player
For you bar chart people, I've done four separate bar charts showing the cards' performance at different resolutions, from 640x480 up to 1600x1200. After that, I have all the info consolidated on to a single line graph with a data table, where each card's scaling across different resolutions is more apparent.

There's an anomaly at 640x480, and I'm not sure what to make of it. The GeForce 6800 is much faster than the 6800 GT or 6800 Ultra cards. I used the same settings for all the cards, and I re-ran the tests multiple times to confirm the results. I'm not quite sure why the 6800 is so much faster than its siblings. It's possible the difference is related to the fact the 6800 has only 128MB of memory—perhaps the game was dynamically enabling some form of texture compression or the like. However, all of the seemingly relevant variables related to texture compression were set to "0", so I am at a loss. Things do snap back to normal at 1024x768 and above.

The Radeon X800 cards start out well with strong scores at 640x480, when they're not limited by fill rate (or pixel-pushing power). As we move up to higher resolutions, though, the Radeon X800 cards' performance drops much quicker than the GeForce 6800s. Amazingly, the $299 GeForce 6800 is within five frames per second of the $499 Radeon X800 XT Platinum Edition once we reach 1600x1200. The $399 Radeon X800 Pro trails by miles.

These numbers suggest that ATI's usual methods for boosting effective fill rate, such as occlusion detection and Z data compression, may not be working effectively in DOOM 3. We've seem similar scaling problems in older OpenGL games on the X800. One wonders whether ATI's OpenGL drivers don't fail to make use of the Radeon X800's full capabilities here.

The older cards, the Radeon 9800 XT and GeForce FX 5950, are neck and neck in DOOM 3. I half expected the GeForce FX to do relatively well in DOOM 3, but it hasn't turned out that way.