There's probably not a cut and dried answer to this one.  The best thing
that anyone short of an Intel engineer with a microscope could say is,
"maybe".  The CPUs are designed to operate within a particular temperature
range, both for performance and longevity reasons.  Certainly if the
temperature gets high enough you can expect that the CPU will be damaged.
But you're wondering if there is some sort of non-visible, or latent damage
that might show up later, I think.

Based on the projects that I've worked on, I suspect that your chip is
probably OK.  While Intel provides a particular temperature range for proper
operation, there is almost always a significant "fudge" factor that allows
for short-term operation outside of the published range.

When the CPU gets too hot, the tiny aluminum or copper traces can begin to
degrade.  You probably will not notice a decrease in performance...generally
speaking, by the time the damage is noticable, the chip is no longer
working.  Since the heat sink was very hot, that tells you that it was doing
its job.

Again, this is pure supposition on my part, but I think that I've seen
enough examples and read enough literature to be able to say that if the
heat sink was not so hot that you could not touch it that your CPU is still
OK and should keep working for some time to come.

Drew Dunn
(Almost an EE)

-----Original Message-----

I've got a question that requires the expertise of a EE to answer and I am
hoping one of our resident engineers can do precisely that.

The other day I was swapping out a hard drive on my bench box..... Tomcat
III....233MMX..it is in a open 286 case with a fist rate PC Power and
cooling CPU heat sink / fan.....normally the heat sink feels cool.

I inadvertently loosened the connection to the CPU fan and the PC ran for
around three days.....12 to 16 hours a day...with no CPU fan...just the
heat sink. I finally noticed it last night ......the heat sink was VERY
hot.....I could touch the heat sink but it was cooking.
The amazing thing was I saw no degradation in performance or experienced
any lockups ....and I have been running NT4 with SETI continuously running
in the background...so from the moment I boot I have a constant 100 percent
CPU use.

The computer has been performing perfectly. Of course what saved it was a
67 to 74 degree ambient air temperature....no cover on the case....and a
first rate heat sink with thermal grease....

I started thinking about this and I am curious if the heat necessarily
damaged or over stressed the CPU even though there have been no failures or
abnormal behavior of any sort ? ?

thanks

m

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