I looked at my temps in Windows 7 and OS X 10.6.2 (without SpeedStepFix) and they are identical!
In Windows the CPU gets the same voltage in idle as in OS X, except that in Windows it clocks down to 1.6GHz
(@ default BCLK 133 in BIOS). The only thing that generates heat is the voltage and as the CPU doesn't reduce it any further when it gets clocked to 1.6, there is no point to clock it there, I guess.
0.9V @ 2.67GHz = 0.9V @ 1.6GHz (in terms of temperature)
I seem to be getting kernel panics after following the appropriate DSDT steps for my board (EX58-UD3r) and they're all working correctly, and as shown in the image below AppleIntelCPUPowerManagement.kext is loaded. Although I think because of my current overclock it's causing it to panic. I have 191 BCLK with turbo boost (21x multi) enabled in the BIOS.
I'm guessing the solution is to bring my BCLK back down to 180 and disable turbo boost? I really not sure. Could you possible explain why OS X ups the multi to 22x?
As always, all help appreciated,
You should test new kexts or a new Mac OS X install with no overclock at all.
If your system doesn't panic with normal clocks, then try getting higher and stop when it gives you panics again.