Replacing cpu

[jd1008]

Final update after installing latest BIOS version 49 from HP.

While logged into win 7, 2 minutes later, and the machine still cold,
it crashed!
And this happened 3 times.
The place I am at is a very cold cafe.
Even though outside temp is in the 90's,
here at the cafe, it is about 71 (thermostat).

So, not sure anymore it is the heat that is causing
both Fedora and win7 to crash or freeze.
I think the cpu is/has been hopelessly damaged
when the owner who sent it to me did not realize that
the fan was dead and that is why it was isuing the warning
and shutting down. Subsequent boots did not even issue
any warnings. It would  just freeze  or crash.
So, I had replaced the fan, and re-greased the cpu and heat sink's
surfaces, and cleaned the vent and vanes of the heat sink,
it continued to crash and freeze.
So I think the CPU needs to be replaced.
I found an inexpensive brand new replacement cpu for
exactly same socket as the current one.

Thanks for all of the respondents' helpful hints and links.

Cheers,

JD