I opened it up, there was a lot of dust around the fans, but I didn't see much else wrong. Anything special to look for?
-CEJ
Well, it's open, so blow out the dust.
Listening for the fan, or feeling where the air exits is the way to tell that it is working. Also, placing your hand on the case in the general area of the cpu will tell you a lot. If it's pretty darned hot it probably has a problem. Then again, the case won't get all that hot if the machine isn't on long enough. But the cpu can overheat in as little as a few seconds, or take as long as a few minutes depending on the heat sink.
If you hear the fan and feel its flow, then that's probably not your problem.
It could also be a bad memory chip heating up and failing. If you have two of them in the machine, try them one at a time (being aware that if you use one chip it probably needs to be in the "A" slot) .. If you do not have a second chip, it would be good if you could find a known-good one to swap out with yours in order to test it. Any size would be okay, but it has to be of the same family and at least as fast as the one you now have. (Faster is generally okay, slower generally is not.)
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