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Changing a Fans Voltage/Speed: To cut down on fan noise, you can either buy one of those new silent ones, or slow it down with an easy voltage mod. It's simple to do, though don't stand in any puddles while performing this mod.

Date: February 24, 2003
Manufacturer: N/A
Written By:

I first heard of this "trick" from the guys over at Unfortunately the site is no longer running and it's relevant to our Wet and Chilly review, so I thought I would just go through it here.

It really is a simple trick, and is a great way to cut down on the noise from a fan. The idea of it is quite simple in that 5 volts from 12 volts = 7 volts. So how do we do this?

This is a standard Molex connector from a PSU. There are 4 wires on this and I've labelled them on the picture below.

From top to bottom they are:-

Yellow - 12 Volts
Black - Negative
Black - Negative
Red - 5 Volts

Now your standard 4 pin fan connector will have 2 wires connecting to the first 2 wires of your PSU connector. This gives the fan a 12 volts line (yellow wire) and a negative line (first of the black wires). All we do is move the wire on the fan that would connect to the negative, to the Red 5 Volts wire on the PSU. If you have got it right you will have the red wire from the fan to the yellow wire on the PSU, and the black wire from the fan to the red wire on the PSU. When you put the 5 volts against the negative it cancels out 5 volts and leaves you with 7 volts.

So to sum it up:-
Fan connector red goes to PSU connector yellow
Fan connector black goes to PSU connector red
12 Volts - 5 Volts = 7 Volts.

That really is all there is to it. You can do this one of 2 ways, either cut the wires or if you have some needle nose pliers, you can squeeze the pins and pop them out of the connector to be swapped over. Don't forget, your adjusting the wires on the FAN connector, not the PSU connector. Double check your connections before you hit the power switch, as we at Viperlair will take NO responsibility if you fry yourself or your equipment; you do this at your own risk.

Final Words

This kind of mod works best on case fans, as reducing the speed on them doesn't have as big an impact on temperatures as your Heatsink fan. That's not to say you can't do this on the fan to your HSF, just bear in mind that reducing the voltage reduces the fans speed, and therefore its CFM will be reduced. It isn't of course any substitute for a fanbus/rheobus setup, but if you're sure your not going to want to run the fan at full speed, this will certainly do the job.

If you have any comments, be sure to hit us up in our forums.


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