Jeez, my 8800 was idling at 55° and loading out at around 70° when I first popped her in; so when I unscrewed the heatsink..imagine, about two thimble-fuls of that industrial gray paste just slathered on the core. I knew when it took almost a minute and a half of wiggling the heatsink to get it to unstick there was the problem. It was late at night and I didn't think to take a pic of all that paste smeared everywhere, but I'll tell you, I had to scrape it off with a razor then apply three coats of Arctic Cleaner just to get it to look presentable. More wiping later, and I could finally see the Nvidia logo clearly. Add some Ceramique, replace the heatsink, up the fan from 60% to 100% in Rivatuner and now it sits idle at around 45° with a load between high 50's to mid 60's. Note this was an Evga card, but the other brands probably have the same problem with all that thermal compound acting like an insulator.

And if you're wondering, the card is still whisper quiet even at 100% fan. I can't hear the thing over my 120mm fan on low and my PSU.

yea it totally sucks when they plop on weigh too much thermal compound, i almost fucked my quad-core up because i didn't realized that the heat sink came with the compound already on it... So i buy my own and put it on the processor then put the head sink on, i felt that something wasn't normal so took the heatsink off and was like FUCK theres double the compound... Too much compound is very bad, because it defeats the purpose of thermal compound.