Okay gentleman, we are at our wits end. The Apple care people seem to be clueless and it is making my edit life hell.
Main Problem: Powermac 2.5 G5 will randomly go into sleep mode during video intensive renders (always Final Cut Pro related).
When render begins, the time bar initiates but then the mouse cursor disappears, immediately the computer display snaps to black and G5 enters sleep mode. It must be stirred (key or mouse click) to awake. Upon awakening, rainbow wheel appears and shortly afterwards render resumes. Often this will happen more than once during the same render. Usually preceding or accompanying this symptom will be a strong revving of internal fans. Also it seems that renders under these conditions take twice as long as normal (aside from the sleep delays). Now this has begun to happen randomly even during playback. We
I don't know if this is true, but maybe one of your sensors on the inside is set ON a drive or too close to a heat source so that any kind of heat makes it think your machine is about to burn out, and hence, it goes to sleep automatically. It would make sense to have some sort of fail safe like this in machines that run so hot... but this is a complete guess. You could check the internal sensors and see if they look "off" in any way.