This has been a problem for a while now, but I wasn't playing any new games so I didn't care. However, with Heart of the Swarm coming out soon, I'd like get to get my computer back in tiptop shape. I have a 8800GT and it idles at around 75c. If I put it under load, it reaches 90c before my computer shuts off to prevent blowing itself up. Here's the stuff I've tried already: Used a can of air to clean out the computer. Yeah, first thing I did. It didn't help. My CPU runs fairly cool (38-40c in idle and it never goes above 50c under load), so I don't think it's an air flow problem. Used Rivatuner to boost the fan on my GPU Even at 100% fan speed my GPU still overheats. This does help, but it's not enough for me to play anything semi-demanding. I've had this computer for just under 5 years now without replacing anything with the exception of a hard drive. I'm just worried that it's the old age of my video card and/or power supply that's causing the overheating issue. I'm not sure what else to try other than replacing my graphics card. So I'm either looking for something to try to fix my video card or suggestions on a replacement card. I don't need the best of the best -- just something a little bit better than the 8800GT that I have now.
If I had to guess, I'd say you're right about the age/power. Replacing it might help, but like you said it could also be the PSU. If you want something cheap to just get the job done, I'd try something like this: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125403 ETA: That's assuming you have the slot for it. I thought the 8800GT was PCIe 2.0, but wasn't sure.
What sort of heatsink do you have on the card? Might be worth looking into a 3rd party cooler. http://www.zalman.com/global/main.php