yea, I used Driver clean pro to clean up my nvidia drivers before I installed the GTO2. The GTO2 should be faster in source-based games, as you said. But my real-world results are much the opposite. Previously, I ran the game at 1280x1024 res, and MAX settings (I mean EVERYTHING maxed out...6x AA, 16x AF) and I was getting 40-70FPS on my 6800GT @ Ultra speeds.
Now I'm trying to play the game at the exact same resolution and settings, and I get about 25-34FPS.....I really hope I don't have to do a clean install, as I though driver cleaner was supposed to be pretty good (I ran both the CAB cleaner and the driver cleaner), but I'm not quite sure what to do. ATITool found my max core to be about 560MHz, and my max memory speed to be about 630MHz, so this card seems to be a decent overclocker. I'm not sure why its performance is so poor at 540core, 590memory (X850XT PE speeds). And yes, all 16pipelines are unlocked. Anyone share a similar experiance?