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View Full Version : How to mod fan voltage?


DWM
09-12-02, 09:32 PM
Hey all. I have a fan in my PS that's EXTREMELY noisy. The PS runs cool, so I want to slow the fan down a bit.

The easiest way to do this seems to put a resistor in series with the fan to cut its voltage. That only involves me cutting into one wire too. The question is, what size resistor do I use?

The fan says 0.3A, 12VDC. Am I correct in assuming, then, that the fan's resistance is 12/0.3 = 40Ohms? (V/I=R)

So if I cut the red wire to the fan (the 12VDC line), and stuck a 40Ohm resistor in there, would it drop my fan voltage down to 6V?

Does 6V sound good to you guys? Or do you think that's too low? Maybe a 20Ohm resistor .. that would drop the voltage to 8V?

Also .. a 20 or 40Ohm resistor would be dissipating a couple Watts of power. Would it be okay like that? Or would it die after a while?

Liss
09-12-02, 09:52 PM
i didn't want to bother adding a resister so i just took out the noisy fan and replaced it with 2 quiet fans

JaY_III
09-12-02, 10:11 PM
Much easier to ground (black wire) to 5V....
that way you get a 7V fan, no resistors needed and only takes a few min

Nico3k
09-14-02, 03:09 PM
ive takin a 60mm fan out of a psu i had that was really loud and the temp inside the psu was the same (about 1C hotter) when i put in a low cfm fan.

good luck :D