So her late 2008 aluminum iMac went into a reboot loop on its own... Pulled the plug and pressed the power button, waited 15 secs and plugged it back in. It half chimes and the screen sometimes flashes gray before becoming totally dead. Black screen etc. When it tries to boot you can hear the superdrive but that's all. As I said it does not even fully chimes, just a half chime before getting cut off. I swapped out the ram for some known working ram and same thing. Removed the ram and it beeps. Tried Target Drive mode and nothing at all. The drive does not show up on my iMac and the screen remains black. So I am thinking maybe power supply. However I live in St. Lucia, West Indies and there is no repair place here that deals with Macs. I have been into it once about a year ago to change the hard drive which was an upgrade so I am not scared to go into it again. Is it possible to use a standard PC powersupply in order to check if the Logic Board is good?? I don't mind buying a powersupply and have it shipped to me but I would like to know for sure if this comp can be repaired at a reasonable cost first. Otherwise it will be time to get one of the new iMacs... Any other suggestions???