Fan gets loud - OS X freezes.

Hey folks. I tried searching this first but none of my search strings found anything helpful.

I've got a PowerMac dual 2.5 with a gig of RAM. It's the water cooled one, but I'm not sure that's a factor.

My Mac occasionally gets really loud and then freezes for no apparent reason(fan continues). The system can be pretty much idle when this happens. Maybe a browser open and Adium.

Disabling an openGL screen saver seemed to make the crashes less frequent, but it still happens once in awhile.

It's gotten to the point that I'm scared to leave it unattended. It's terrifying to come home to this thing screeching away for however long.:radioacti

Any help would be greatly appreciated. I'd gladly provide more info if needed.
Thanks in advance.

Sounds like your CPU, or GPU is over heating. Could be a loose heat sink, or bad temperature sensor, or dirty internals.

I would take it to someone who knows how to open up a laptop, and clean it out. and make sure everything is right. Preferably some one who as actually done laptops before, not some one who thinks they can because they've done desktops.

I agree with Ice Cream Man, it's almost certainly a C/GPU overheating issue - the fact that it happens quicker when the system is under load is a givaway.

If it's watercooled, the issue could be a dead pump (assuming it has a pump)or an unseated heatsink. Either way, you need expert help - I'd take it in for a service.

Thanks for the feedback fellas.

It doesn't necessarily happen under load. In fact it happens most often when I'm not using it. I can do plenty of CPU intensive stuff without the fan even getting very loud.

Maybe it's some system process that kicks in after a certain amount of idle time.

Anyway, I saw some mention of dashboard widget that has temp readouts. Maybe I'll start there.

Thanks again.