I have a 7950GT 256MB. In some games, characters/object are missing polygons (they are see through). Also, when there is a large field of view, flat polygons that kind of look like ramps appear randomly throughout the maps.
What could be the problem? I'm using Win2k Pro with all the latest drivers. The CPU (pentiumD 805) is overclocked, but everything is cool. The CPU is <50*C, the GPU<50*C, and case temp <30*C.
The games I play that have problems are TrackMania Sunrise Extreme, UT 2004, and Battlefield 2 and 2142.
Are you running driver default quality settings or did you slide them toward performance? You could try to set the drivers to High Quality instead of default and see if that helps. Quake is OGL, so it seems it's DX games that you are having issues with.