I just got a 1.6 ghz imac G5 and it keeps falling asleep whenever I try to play higher-end games. It has happened with a demo for Halo, with marble blast and nanosaur2. This problem just started today. It seems to fall asleep every 30 seconds or so.
Prior to today, it didn't have issues. I tried turning sleep off completly and I even reset the pram (tech support suggestion) but it's still happening. Any suggestions?