recently, I have noticed strange behaviour of my CPU temperature: idle temperature has risen -- without any obvious reason -- by nearly 10 deg C, BUT the temperature at 100% load stayed exactly the same! Have you got any idea what had happened?
My system: Athlon XP 1700+ Thoroughbred (has on-die thermal diode), MB: Soltek 75FRN3-L (does indeed read from the CPU thermal diode, unlike many others). I'm using SpeedFan and not any other MB monitoring program, so the answer is not that some other program is changing the calibration (ie. offset, mult.) of the temperature reading. I don't have any case yet (Open Air PC :-) ). Fan RPM did not change.
My only explanation is that the thermal paste (included with a Zalman heatsink) underwent some change because of which its thermal properties are worse at lower temperatures, but same as before at higher temps... But I very much doubt that. What do you think?
Oh, I'm sorry, I've just remembered... Probably around the time I noticed this behaviour, I remember installing Soltek's motherboard "drivers". And these probably change the hardware monitring chip's (Winbond 83627HF) settings.
So, now, I don't know whom should I trust. But 42 deg C when idle with my setup is truly nonsensical. The lesson we can all learn is that we can't trust any temperature reading (actually its absolute value, the temp. differences will be quite accurate) to be better than +- 10 deg C accurate...