My dad gave me this computer and it has always had a noisy fan. I can live with that, but now it is overheating and shutting itself down. I don't know if it is a fan or a drive that starts up and runs really fast and loud, then the computer shuts off. I always thought it was the fan, but now am not sure. I have moved it to a place where it is exposed to more air, but that has not seemed to help. Does anyone have an idea or solution to this problem? The nearest Mac dealer is about 80 miles away, so if I can fix this on my own, I would like to try. Thanks for any help you can afford this desperate iMac owner.