Asus P2B series motherboards do not
support temperature monitoring
of the thermal diode available in many Intel processors, however they
are able to monitor CPU temperature externally using a thermistor
connected to the JTCPU header (May be labelled differently on some
versions, e.g. the P2B-D and P2B-DS have headers for both CPUs,
labelled JP4 and JP5). While it is possible to connect CPU thermal
diodes to the CPU temperature monitoring headers, this is difficult as
it requires a moderately complex interface circuit installed on a
modified slot-1 adapter. Using external thermistors is considerably
easier!
External thermistors cannot provide an
accurate reading of CPU core
temperature, however they do provide a useful relative indication of
normal CPU operating temperature and can alert the user to abnormal
increases in temperature which may be indicative of a cooling problem.
The Asus P2B series boards were designed
to use 10K ohm thermistors
for CPU temperature monitoring. At least two styles of thermistor are
available.
The green 10K ohm thermistor
(top) is a pigtail type, available at Radio Shack. This type is not
ideal for P2B series boards running Socket 370 processors as it is too
thick to fit close to the CPU core. Red axial lead 10K ohm thermistors (bottom) are not as commonly available, but are better suited to this application as they fit between the CPU and heatsink. |
The parts required to make a CPU temperature sensor for the Asus P2B are shown at left and can be obtained from any good electronic component supplier (Radio Shack does not qualify)
The two-pin reset or power switch cabling from a discarded ATX PC case can be used in lieu of new parts if desired, reducing the parts list to just thermistor and heatshrink tubing. |
Assembling the CPU temperature
sensor is straightforward. First bend and trim the thermistor leads as shown. |
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Next solder one end of the twisted pair cable to the thermistor leads. |
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Then solder the header pins to the other end of the twisted pair cable. Crimp the lugs onto the insulated portion of the wires to provide strain relief. |
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Finally, insert the pins into the header casing, slide heatshrink tubing over the thermistor, and warm the tubing with a hair dryer to fix it in place. |
Last updated April 3rd, 2004 by p2b@sympatico.ca