I'm going to be trading a friend of mine's computer. He has an iMac G5, but the fans are constantly on and it sounds like its about to take off and fly. His video messed up and Apple replaced it. After that, the computer is running properly and its just the fans now that seem to be running in full blast. His imac is a Rev. A 17" iMac 1.8Ghz G5. If anyone has had this problem, let me know how you got to fix it. Thanks!