[Mini-Mod] Easy way to slow down your fans.

I rebuilt my cooling system today, and i was left with a blowhole on the side of the case, without a fan. I took apart some old PSU, ripped the fan out, and cleaned it. It had no molex connections or fan stuff, just bare wires - i ripped it straight off the PCB.


On 12v, the fan was *very* noisy, but it also moved a great deal of air. My fancontroller and all MoBo ports were already filled with fans, so i thought of another way to slow it down a bit.

Looking at a standard ATX plug, from left to right, it is yellow-black, black-red.

Yellow = +12v
Black = 12v gnd
Black = 5v gnd
Red = +5v

On 5v, the fan ran much too slow to provide any cooling, and on 12v it was way too much. Hmz. Well, time for physics!

Voltage = the potential difference between two points. Connecting a device to the Yellow (12) / Black (0) ATX ports, provides 12v, since the difference between 12 and 0 is 12. Same with +5 and 0, the difference is 5v, so theres 5v provided.

Now if we connect something to the +5v and the +12 leads, what will happen? The difference is 7 (12-5=7), so it should be 7 volts...guess what..right! Physics is easy, isn't it

So if i connected the fan to the Yellow and Red wires, it would be running on 7v, a nice average for cooling / loudness. I took another nosedive in my box of parts, and came up with an old ATX plug set.

I stripped the Red and Yellow wires, and soldered the red / black fan wires onto them. (Yellow = Red, Red = Black. bit confusing ) After that, i just connected the ATX plug to the PSU, mounted the fan in the sidepanel, and voilá, all is up and running fine.

A small, but satisfactoring (whatever the word) mod, speaking from myself


Next is a pic of the solder job - really easy

nice, and dude physics is hard, it's my major, nice mod though

you can use a DPDT switch to do something like that for low, mid, and high speed. Or a simplier one which is a SPDT switch for Low and High speed selection.

Nice mod, that's a lot cheaper than buying a fan controller!

Ive done that before, is there any other way to slow a fan down w/o a controller?

This is also known as the 7v mod.

Yuriman said:

Ive done that before, is there any other way to slow a fan down w/o a controller?

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unplug it.

I find it works very well for slowing them down.

Yeah unplugging them does have the unusual affect of slowing down fans and thus making them quieter

Seriously though, get a variable resistor..

Temps before and after you did the mod? I might can do this on my 92mm Tornado. Using it now as a intake fan.

This fan is only mounted in the side panel, cooling the upper side of my VGA. No noticeable temp difference on the cpu or case. but because it is very quiet now, it can only do good

Tebore said:

This is also known as the 7v mod.

Click to expand...

Yeah, but i just tried to explain it a bit and show people how easy it is.