The issue is not dealing with the motherboard's circuitry in my case.
Some observations:
The use of a diode reader tapped into SMBus just doesn't work for testing. I am seeing 5-10C increase in temperatures by booting the test PC into DOS mode and running K7Burn while monitoring the CPU temperatures with a second PC.
And what of calibration? What value is a diode reading without knowing how the diode deviates from the true temperature? So my major concern was:
Once you have a way to measure the diode temp, how can you calibrate it?
One could in theory put the whole system into a temperature-controlled chamber, adjust the temp, and then record what the diode reader reports vs. what the actual air temperature is. I lack this equipment or the energy to pursue this avenue.
Another idea is to calibrate the diode and reader vs. a much better thermometer in a water bath. By adjusting the temperature of the water over a fairly wide range one can MEASURE the error associated with the exact diode in the CPU you are using and with all your wiring. This is no problem since the CPU works fine as a diode without power. What IS a problem is that if you calibrate via one method (maybe wire wrapping to the pins) and then use a different method to actually connect the reader to the motherboard (soldering onto the socket pins) then your calibration is worthless. We are talking about resistances in the ohm range substantially affecting the diode reading. This is incidentally wh
Based on all of this, I decided to permanently affix the wires to the CPU pins. Now I can use the exact same setup (wires, CPU, reader) in calibration and in testing.
This was the only way I could devise to approach reasonably useful numbers for a diode reader.
Hope that clears things up...
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