I've started using SpeedFan to monitor my temps, and I have four channels: System, CPU, AUX and HD0. The system matches the northbridge measurement from PCProbe, and the CPU temp matches the CPU temp from PCProbe, and these channels give believable numbers. I'm not heavily using the HDD, so HD0 temp stays around 27C without too much variation.
My question is what might the AUX channel be? There was no similar channel in PCProbe. The AUX channel reports temps that are generally 18C or so cooler than the CPU. I relate AUX to CPU because the AUX temperature rises with CPU activity. However, the characteristic is very different. For example, if I load my CPU to full, the CPU temp eventually reaches 55 to 56C, with the AUX at a little over 30C. When I bring the CPU down to 0% activity, the CPU temperature slowly comes down to about 32C (first-order response). The AUX channel, however, reports lower temps immediately (step-function). From this I would expect that the CPU temp is associated with the case or core temp of the CPU, and the AUX is either close to the CPU, or is a temp measurement on the Mobo.
Does anyone have an idea as to what the AUX channel is reporting?