I use a Sapphire 4850x2 2gb card. I run ten accounts on it but most of my heat issues come from the fact that my room gets above 90 degrees every afternoon and sometimes over 100. It's been getting up to around 110 outside here and my ac can only handle so much. All the electronics really heat the place up.

I'm not saying heat is your problem but it's just something to think about or look into. It seems to me that alot of these type of threads pop up in the summer time. One of my friends keeps his computer running by putting 2 ice cold beers into the case every two hours or so. Ice packs would probably be a little less ghetto but you have to work with what you have.