I have a power pc 20inch iMac with overheating issues. What happens is it will start overheating and force itself to sleep and wont wake back up until it cools down (this is all verified in the console). It's repair history is as follows; 1. logic board replaced (overheating persists) 2. new fans installed (overheating persists) 3. currently at repair center with stumped techs.... I'm stumped & quite frankly a little ticked off about this. Any questions or comments about this issue are welcome.