Note: The problem I had with the Dawn of War demo was a result of using high quality shadows. The solution was to lower the shadow quality to medium.
I was going through the tutorial in the Dawn of War demo when I noticed the following graphics corruption on the X800XT, which I outlined in yellow. When I changed the viewpoint, the corruption usually disappeared, but would sometimes reappear in a different orientation at the new viewpoint. I used a variety of AA/AF settings and resolutions, but the problem continues to persist.
I had a similar problem with the Radeon 9800 Pro and Call of Duty when I was reviewing a mini-barebones system earlier this year.
But I never figured out what caused the corruption or how to go about fixing it.
Any ideas? I ran the game without FRAPS and also tried rebooting the PC. Maybe a driver bug?