One of the machines is a newish dell btx, that's having major cooling
> problems (random page faults, hd temp goes up to about 130 F, etc). I
> narrowed the problem down to the main case fan, which is a four pin
> PWM (pulse-width modulation). Apparently, the bios (happens without
> hd/os) forces the fan to spin at a ridiculously low speed,
> approximately 10% of capacity.
If it's newish, call Dell and have them send you a new motherboard, or a new fan, or both, under warrantee.