So I've done all I can find on the internet on helping my broken computer. It used to have the noisy fan issue and then it would shut off. Now after being off for 12 hours, it may shut off in 2 minutes, maybe in 30. I have reset the SMU by unplugging for 10 seconds and then plugging in while simultaneously holding the power button, then turning it on. Ive also reset the PRAM, but it still seems to shut off. Is it a bad power supply? I dont ever hear the fans blowing hard anymore. If anyone has basic things to do, I'm all ears. I know last step is probably just reinstall OSX. I'm on 10.4 right now.