I got my tube of IC Diamond Compound the other day. Supposed to beat Arctic silver in most cases. I put it on my CPU and even though I have never cracked open a Video Card, I managed to replace the old cement like compund in my GPU with the new IC Diamond.
Been running a few days and everything runs great. Do not have exact temp comparisons to give because I did not do any tests, but both run a good 10+ degree F cooler at idle, As for the GPU under load, not sure as i have my Fan Control set on a steep curve, so it can be at same temp as before but will be doing so with fans at a lower speed.