I originally RMAed my 6600GT for instability a default clocks, and the one I got back was not DOA per se, but effectively useless. In a couple different systems, the image was just a garbled mess, and I haven't been able to figure out what's wrong with this. Both PSUs should have been sufficient for it, so I'm not really worried about the rest of my systems. Any ideas on how to go about fixing this?