controlling a fan's speed

I'd like to be able to control the speed of my case fan. I tried SpeedFan, but it did not play nice with my mobo. Is there a way to tweak the OS to control fan speed?

System:
HP Pavilion 753n
Pentium 4 2.52GHz
1.5GB RAM
ATI Radeon 9550 AGP

 

There is no control built into Windows to control the speed of a system fan - though some manufacturers will include programs which allow you to do this.

In this particular case, I think you'd be best off using manual control through a variable resistor between the fan and the power supply. Unless there is some kind of BIOS level control over temperature regulation and fan speed.

You could get a bit fancy and use PWM (pulse width modulation) to more precisely regulate fan speed depending on temperature
http://www.benchtest.com/wcooler6-2.html