CPU Overheating

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My CPU (AMD 2800) has begun overheating.  It runs about
68C when idle, hits the 72C threshold when working.  The
CPU heatsink is hot to the touch.The MB is 30C, just 4
degrees above room temperature.  All fans including the
CPU fan are working.

It stopped twice last night.  Until then there was no hint of a
problem.  I hadn't looked at the CPU temperature since the
MB was first installed (fall of 2003) - it was normal.  The PC
Probe was not installed (it is now).

I dropped the clock multiplier to 10 from 12.5 so there would
be some function.  That reduced the CPU temp to 61C.

What would cause the CPU to start overheating?  And what
should I do about it?


    AMD Athlon XP 2800 at 2145MHz (12.5 x 166)
    ASUS A7N8X Deluxe MB
    512MB RAM
    30GB Maxtor Drive
    160GB WD Drive (shown at 38C)


Re: CPU Overheating

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I thought I would answer your question before I go up and thank those who
helped me with the same problem.  Take the fan off of your heatsink,  the
heatsink is probably covered in dust,  remove the dust,  I took an air hose
to my machine and blew it out.  Reduced my CPU temp to about 48 cel.  hats
from about 75 - 79 cel before I did this.

Re: CPU Overheating

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Thanks, that dropped the temperatures down to 55C idle, 66 busy.  That
is still higher than I think it should be.  The Radio Shack heat sink
compound might be suspect as was not completely cleaning the old
compound off.  What did you use for heat sink compound?

Thanks again,

Re: CPU Overheating

On Thu, 7 Jul 2005 12:13:06 -0400, "Gary Brown"

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Radio Shack compound is sufficient if not overapplied.
However, if it is old, if separated and too thick, then it
may need stirred up some.  It is more difficult to do in a
tiny metal tube but still possible, IF necessary.

If you used a premium compound it might lower temps a couple
degrees- not enough to be worthwhile unless you already had
this other compound.

Re: CPU Overheating

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Did you check if the heatsink is actually against the CPU?  Sometimes
the plastic tabs on the socket break or the retainer snaps off so the
heatsink is no longer pressed against the CPU.

You said your CPU has "begun" to overheat but make no mention what the
temperatures were before.  So how do you know that it wasn't always
overheating?  Could the jobber (maybe you?) forgot to peel the tape off
the thermal pad on the heatsink before affixing it atop the CPU.  Or
they forgot to put a rice kernel size gob of thermal compound on the
heatsink, spread it, put it on the heatsink, twist a couple times, and
then snap the retainer on the socket.

It is possible that you have let dust accumulate so badly within the
case that it is blocking airflow.  Even if there is enough space for
airflow between the fins of the heatsink, dust is a thermal insulator so
you don't want it coating the surfaces from which heat is radiated.  Get
a can of air and blow out the fan and heatsink.  The dust might stick to
the fan blades so you can use an ear swab to wipe it off and then air
dust again.  Make sure the rear panel grill or fan are also clean, and
the same for blowing out the power supply unit of dust (you can usually
blow through it since opening it voids the warranty, if there is any
time left left on the warranty).  Make sure the front intake is clean.
Arrange your cables to move them out of the airflow path, and orient
ribbon cables so they are parallel to the airflow (so they don't act
like big baffles that block the airflow).  Make sure the ribbon cables,
or any other cables, are laying against the CPU, its fan, or around the
memory stick so they don't block the airflow.

Do NOT use a vacuum cleaner inside your computer.  Household vacuum
cleaners create static due to the volume of airflow at the hose end (so
insulating the metal end doesn't help since static will still build up
on plastic).  Very few of the "computer" vacuums are meant to be used
inside since they also build up static.  They are designed to be used to
clean your keyboard, not circuit boards.  Static resistant vacuums are
expensive and hard to find.  So just use a can of air to blow out the
dust, and do it outside unless you really enjoy putting the dust back
into your room.

Even though the CPU fan is spinning, is it spinning fast enough?  You
could use SpeedFan, Motherboard Monitor, or a monitor utility provided
by Asus to check the fan speeds.  If you are running SpeedFan, another
fan noise reducing program, or your BIOS has settings for fan speed
control, or you inserted fan controllers inline with the power to the
fans, disable or remove them or set them to 100% fan speed to see if
they were running too slow.  Check the PSU fan is spinning.  The CPU fan
running at 100% will still have problems cooling the CPU if the heated
air doesn't get removed by the PSU fan (or a backpanel fan).

Just what are you using to determine what is your CPU's temperature?
Are you going into the BIOS screens to check its PC health screen that
reports temperatures?  Are you using an Asus monitor utility and, if so,
are you sure you got the right one (so it is using the proper lookup
table)?  Are you using some 3rd party monitor utility?  Using the wrong
version of a utility could result in using the wrong lookup table.  For
example, if you use SpeedFan or Motherboard Monitor and pick a chipset
that is wrong, the temperatures reported will be wrong.  The readings in
the BIOS screens don't rely on any software you may load in Windows.

Re: CPU Overheating

On Tue, 5 Jul 2005 20:57:27 -0400, "Gary Brown"

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Provided all fans are still working, it is typically dust
accumulation or a rise in ambient room temperature- which
would raise the CPU temp by a corresponding amount.

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