[new-nickname-zanovo]

I've got an old server, which I intend on using at home. Currently it's way too loud.

Has a 24V .4amp 90mm fan blower. If I can't get a software solution to slow the fan, what would I need to do to reduce the fan speed - can I just put a resistor in there?

It has 4 cable connections, two black, one red and one yellow. I'd need to measure the volts with my multimeter to work out what each one does. Any thoughts?

UK based - I thinking of wiring in a variable resistor, or is this not the way to go? If I did, what would I be looking for?

Edit -

http://www.blackfiveservices.co.uk/fanspeed.shtml < gives an online calculator for working out the resistors required.

Think I'll be dropping it down from 24Volts to about 16ish.

Code:

Code

Original fan voltage: 24V  Original fan current: 0.40A      V=IR (Ohm's Law), so 24 = 0.40R   =>   R = 24 / 0.40   =   60  Fan resistance: 60 Ohms  Target voltage: 16V      V=IR (Ohm's Law), so 16 = 60I   =>   I = 16 / 60   =  0.267   Target current: 0.267A  Voltage drop across resistor: 24V - 16V  =  8V      V=IR (Ohm's Law), so 8 = 0.267R    =>    R = 8 / 0.267    =  30   Target resistance:  30 Ohms  Power dissipated by resistor:  8V * 0.267A  =  2.133W

So I need 30 Ohms of resistance, able to handle about 2.133w. Looks like I'll have to get a few cheap 5ohm resistors and wire them all up, IIRc they usually only handle about a 1/4 of a watt so would need atleast 8, likely 9. Just got to work out that maths now. God I hate electronics.

Acutally, now I'm even more confused.

I need 30ohms, capable of handling 2.1333 watts give or take. What resistor, or combination of resistors can do this?