I posted about this in
Genereal Discussion a while back and havent had the issue since, however it started again today.
What happends is that the screen will go black and the fans will speed up as if first booting up the machine, but for a couple of seconds the sound is still running which then stops and repeats itself as if stuck. But the machine doesnt actualy turn off it just sits there, I have to hold down the power button to turn it off.
This doesnt happen when I am just doing nothing on the comp, however it has happend once or twice when I turn it on again right after it has happend.
It seems to me like its the power suply, as the temps dont seem to be that high when I reboot and temp check. the main thing that makes me think this way is that it doesnt happen if I am not underload... it will happen at random times in games for instance I was in SRO for around an hour before it did it last time, but when I booted up counter strike source is shutdown as it was loading the program. So my guess is a power issue maybe the power supply is dieing and cant take the load anymore... however its funny that it doesnt do it everytime which is what is confusing me.
Any Imput would be greatly appreciated.