Another mysterious heat problem involving CPU transfer

[Jeff7]

This is another bizarre story. Same CPU, same heatsink, different motherboards, different temperatures.

I transferred a 750@933 T-bird at 1.85 volts from my Epox 8KTA3 motherboard to a Soltek SL-75KAV. All voltages are the same; the speed is the same; both have arctic silver, both are using the same heatsink and are running the same rpms. The differences:

- On the Epox, the surrounding temp was 30C, but the processor temp was 43C

- On the Soltek, the surrounding temp is 23C, but the processor temp is 56C.

The heatsink is not off center either; I tested for that by applying light pressure to each corner. All resulted in a sudden temperature spike, even reaching 74C briefly. (not even a lockup at that temp)

What the heck gives here? I don't think motherboard monitor is reading wrong, because the BIOS reports similar numbers, plus the heatsink feels quite in line with MBM's reported temp.

 

[Imperium97]

Different motherboards read temperatures differently so don't worry too much. You can't compare CPU temps between different motherboards for that reason. Temp readings for AMD chips are pretty innaccurate anyway (although finally they have started putting an on-die temp diode in the new chips)

BYW: The higher temp is probobly closer to your actual CPU temp, mainly because AMD chips run hot.

 

[Jeff7]

Hmm, yeah, I think I see another way that'd be possible; the Epox board has a bulb-shaped thermistor under the CPU, while the Soltek's sensor is the flat, compact type, so it's probably more accurate. Guess I should invest in one of those displays that is simply designed to show CPU temps, etc.

 

[Imperium97]

The main problem is, AMD's don't have an internal diode so you never truly get the CPU die temp anyhow. Mikewarrior2 has done a lot of looking-into on this topic and you can see his findings HERE I believe AMD finally put a temp diode (like on the p3) in the new Palomino cores.

As long everything runs without crashing or giving wierd errors, you'll probobly be fine.