Hi!

Check the power supply fan. You may need to replace the power supply
at this point. I had a slimline Dimension E521 cross my bench that was
doing the same thing. The PSU fan had quit running and things got so
hot that the supply was barbecued.

Dell's power supplies are typically good quality, although they have
been cheapening them as of late in the "home grade" Inspiron and
Studio models.

I was given a Dimension 8100 recently that ran fine in every regard,
although the longer it ran, the more regulation noise could be heard
from its PSU. I didn't give it too much thought until I put my hand
back there and felt no air coming out. The PSU fan had stopped. Even
so, the system ran normally for as long as I cared to use it. I was
even more impressed when I opened the supply to repair the fan--it
hadn't suffered in the least.

They sure don't make 'em like they used to...

William