[Darthtanion]

I have never been a big fan of system-regulated thermistors since I've never been convinced that a diode knows more than I do. You mentioned that the case fan acts up at the same time that the HSF does? If this is the case then it sounds as if you have the fan for your processor cooling attached to one of the 3-pin headers located on the motherboard. I usually recommend staying away from this setup as the power draw of a decent fan can be too much for a motherboard to handle. I always attach my primary cooling fans directly into a 4-pin Molex from the power supply. If you don't have a means to attach it in this manner, you can pick up a 3-pin to 4-pin converter for very little at most decent electronics stores or online.

If you're bound and determined to use the motherboard header, then take a look in the system BIOS and you should find a setting that will disable the automatic fan speeds from kicking in.