A7N8X invalid CPU temp issue

[Kroagnon]

I just bought a A7N8X rev 2 from Newegg.com. It is loaded with the 1007 BIOS
(latest). Problem is, it is reporting in excess of 75 degrees Celsius on a
cool CPU (XP 1700+). I watched the temp meter in the BIOS shoot from 33 to
74 in a split second. Normally I would just ignore it but it is shutting the
system down and I can't seem to find an override to stop it.

The CPU is fine as I was able to put it in an Abit KG7 with hot temps under
45 C. I have another A7N8X rev 2 that I've had for about 6 months running a
2400+ with no such issues. Anybody know what's wrong with this thing? I'm
ready to RMA it.

 

[Paul]

I just bought a A7N8X rev 2 from Newegg.com. It is loaded with the 1007 BIOS
(latest). Problem is, it is reporting in excess of 75 degrees Celsius on a
cool CPU (XP 1700+). I watched the temp meter in the BIOS shoot from 33 to
74 in a split second. Normally I would just ignore it but it is shutting the
system down and I can't seem to find an override to stop it.

The CPU is fine as I was able to put it in an Abit KG7 with hot temps under
45 C. I have another A7N8X rev 2 that I've had for about 6 months running a
2400+ with no such issues. Anybody know what's wrong with this thing? I'm
ready to RMA it.

Things that make a CPU hot:

1) VID code requests higher than normal Vcore voltage.
Processor power is proportional to V**2
Root cause - fault in motherboard copper tracks.
2) Processor or component underneath socket is shorting or
partially shorting Vcore power. Heat is generated.
Root cause - same as (1), or a brass standoff could be touching
a power track.
3) Clock rate being used by processor is higher than allowed.
Processor power is directly proportional to Fcore.
4) Heat sink is not installed properly. I seem to remember that
a 180 degree rotation can result in poor cooling (I don't
have an Athlon motherboard, so cannot comment on that).
5) Heat sink is not making good contact. If thermal interface
material doesn't fill the gap, temperature will shoot up.
Since the Athlon uses a bare die, establishing a good contact
between the small contact area of the die and the heatsink is
crucial to it working. Check that the heat sink is not installed
on an angle (tilted) - I've had one motherboard, where the
lever arm on the processor socket prevented the heatsink
from seating properly.

It is a good idea to install the processor and HSF while the
motherboard is outside the case - that way, you can hold
the motherboard up, and inspect the HSF from all sides, to make
sure it is installed properly. Verify that the way the bottom
of the heatsink is milled, lines up with the position of the die.

Try the cardboard test - install a minimal set of components on
the motherboard, while it is sitting on a piece of cardboard.
See if the symptoms are reproducible. Check frequency settings,
Vcore voltage, and temp in the BIOS. RMA if necessary.

HTH,
Paul