Resistance is proportional to temperature, so measuring resistance over a
circuit (through a diode, for example) can be mapped to temperature.
Whatever you'd use to measure resistance would have to be calibratable (use
digital temp. probe on die surface, and insulate entire CPU surface to
simulate interior of die temps.).  In addition to a zero point you must take
temps over the entire range you'll measure, and correlate to the resistance
readings (Excel can help with this).  The key problem here is hooking your
resistance meter up to the unused CPU element you will use.  Of course, you
must identify an unused CPU element first...

This is not really a worthwhile endeavor IMHO.  Better I think would be
several temp probes (one on each side of CPU?) and use average, then
correlate to actual CPU temp by measuring when CPU is fully insulated.
Martin Kurr
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> ----------
> From:         Kenneth Alan Boyd Ramsay[SMTP:[log in to unmask]]
> I understand that certain semiconductor diodes can be used as a sensitive
> thermometer (although they may be tricky to calibrate).  If you could use
> two legs of an unused transistor, or some other diode on the CPU die, you
> should (at least in theory) be able to follow the actual die temperature.

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