PBG4 DVI 12-inch and heating issues

[Redjack]

So my PB is sluggish (has been for the last year) and everytime I play YouTube videos (much less DVD movies), the system overheats in like 5 minutes. Within 10 minutes of this overheating, the system automatically goes to sleep (too much heat I guess). It's usually when I'm playing music or video.

Does my PB need a new cooling fan or heat sink? I don't know which parts are for what, help!!!

 

[tomlee59]

Do you hear the fan come on? If not, that's a problem...

Are the vents unobstructed (internally and externally)?

Is the G4 sitting on a hot plate?

I have performed sustained, heavy-duty number-crunching on these, and have not had overheating problems, so something is broken/clogged on yours.