Okay, I have been trying to figure this **** out for a while now. I think the problem some people are having with Speedfan is because as someone mentioned earlier, it reads sensors from all over the MB, and some MB have heaps of sensors and some don't have many.
I've been running Orthos for 2 hours now with my CPU at 3Ghz, and Speedfan says:
Temp1: 30C (MB?)
Temp2: 47C (CPU - t_case?)
Core 0: 55C
Core 1: 55C
Everest gives me:
From this, I'm guessing that Temp2 in Speedfan and CPU in Everest are reading the t_case temps, and Everest is adding that 15C mentioned earlier that TAT and CoreTemp add to the Core0/1 sensors.
Also, during an earlier OC my Speedfan readings for Core1/0 hit 63C and the Temp2 (t_case?) reading hit 61C. What's interesting is that I had set my BIOS to sound an alert if the CPU hit 60C but it didn't happen, so obviously the BIOS is not reading the higher Core0/1 temps and is relying on the other sensor, which I think is t_case.
It's speculation, but perhaps the reason the BIOS alarm still didn't go off when Speedfan's Temp2 hit 61C is that Speedfan errs a couple of degrees higher as a safety margin?
Basically, as I stated I think people that are having trouble with Speedfan are not getting there t_case temps monitored for some reason, but also I think it is clear that the Core0/1 temps are much higher than the maximum limits stated by Intel, even when we take the 15C error in some systems into account.