1 post • joined Saturday 24th November 2007 04:49 GMT
Tony, I had a similar problem with my iMac G5/ 1.8MHz system. The fan would roar shortly after startup, and then the system would become unresponsive. I ran the Apple Hardware Test from the restoration CD which revealed a defective RAM module. When I exchanged the module, everything worked like an Apple should. Flawlessly. Give it a try. That would be a simple fix.