iMac shut's down by itself...

[charlie.mo]

My iMac (21.5") turn off by itself and it doesn't turn on until I unplug the AC from the back and let it rest for at least half hour!!! If I try to turn it on I only get fan and drive noise but no screen at all... The longest time I let it rest, the more time that I can use it. I already reset PRAM. I'm runing 10.6.3 and the biggest software I use is ArchiCAD 13...

Does anybody have a similar issue with his/her iMac?

PS. Sorry, I don't speak/write good English but I did my best...

 

[natewsmith]

I'd just call Apple Care and have them ship you a new unit.

 

[Hellhammer]

Sounds like a PSU or logic board issue. Call Apple ASAP and get it fixed