• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

Variable Speed Fan Control for Multiple Fans

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.


Oct 6, 2002
The Sunshine State
Sticky =)

First off, why does anyone want to continually turn their fans up and down? Well, after my Delta Experience I decided the next box would be as quiet as I could get it, within reason, without going water, or less performance. If you've lived with a Delta, you know what I mean. So I bought 3 - 80mm Enermax Case Fans, the pink-purple ones with clear blades, and screw adjustable speed controls. These are nice little fans for $8 US, but the only hassle was swinging the side cover open to adjust the fans up and down. After building the project below, I simply turned the adjustments all the way open on the fans, and use the front face plate mounted adjustor now. When it's cool in the morning and evenings, I no longer have to listen to ALL of the noise ALL of the time.... (didn't Abe Lincoln used to say something about that?)

I have a Blackish/Charcoal Chieftec Server Case DX-01BD

Basically, I did some reading, found out that to adjust the voltage supplied to the fan bus, you can use an LM317T Voltage Regulator chip, a small, cheap potentiometer, and a resistor or two. (Be sure to put a substantial heatsink on this chip !) A trip to the local Radio Shack (only thing we have), produced the electronic parts I needed, I had the rest (we'll say 'scavenged').

Stuff Needed

LM317T Voltage Regulator $ 2.00

5K Ohm Potentiometer (didn't have 2K) $ 2.00 ?

240 Ohm Resistor (pack of 5) $ 1.00
180 Ohm Resistor (pack of 5) $ 1.00
L.E.D. (pack of 2) $ 2.00 (or scavenge from an old electronics piece)
L.E.D. Holder Had one (scavenged)
Knob for Pot. Made one (scavenged)
Little Circuit Board Had one
Some sort of stomper heatsink material for chip Made one from old PSU Heatsink (scavenged)
Various Drill Bits and Drill
Various Wire to reach the FanBus, and Shrink Tube or use some lengths of stripped insulation from some wire (for the LED legs)
Soldering Iron, Heat Sink Clips, Solder
(Don't use that biga$$ed Weller on your electronic parts, use a real one)
Hot Glue Gun
Mr. Dremel and all his friends (and a boatload of Cutoff Wheels)
Patience Level: Pre-Saint on a Scale of God-Like

LM317T Voltage Regulator
1 to 27 volts
1.5 amp
Vi- Vo= 5 V, Io= 500 mA, IMAX= 1.5A and PMAX= 20W

Using a pre-drilled Circuit Board to mount the Voltage Regulator, the Resistors, the Common Points, and little jumper wires where needed, not only holds everything in place, but gives it a nice 'professional' ghetto look.

If you have a spare face plate to practice on, that would be cool. Since mine are black, I don't have a lot of them lying around, but I did have some white ones to test with. You can find out what size you'll need for drill bits, and prefit all the parts before you're committed to the real one. I have a swinging cover door on my case, and originally the knob wouldn't allow the door to close all the way. So, out with the Dremel, hack off more of the pot's shaft, and slice a nice little chrome knob in half, and that took care of that.

I again used Mr. Dremel and the cutoff wheels to make the board narrow enough to fit on the bay cover. Don't know whether it was late, I got a bad batch of cutoff wheels, or it was the crack, but I think I went through about 12 or more of them. That was a record. Then after all was soldered, and TESTED**, I used a Hot Glue gun to secure the board to the back of the cover. Very slick, too. And, from first hand knowledge, you can easily pop it off to, um, maybe move a resistor lead that somehow got soldered in the wrong place, preventing anything from working, and reglue it.

TESTED** I would suggest putting it all together with alligator jumper clips or something to see how the parts go together. I used an old 200watt psu I have jumpered to allow me to use it without being plugged into a motherboard. Then, when you have it all soldered, test it once more before glueing, and mounting. It's a lot easier to fix something before it's mounted than to take it all apart and do it right the second time...not that I would know or anthing.

One thing: At first I used a flimsy little heatsink I'd scavenged, until I actually touched it ! Whew, that bad boy was HOT. So I cut up some stout aluminum ribbed heatsink I scavenged from a powersupply (you can see it in the picture above), and used some good ol' Arctic Silver II (that was all I had available... where's that cheap crap when you need it?) - and it's a LOT cooler. Looking forward to evenings and mornings. Maybe I can just siesta out when it's toasty, not have to listen at all. hahaha.

Anyway, I think we have a winner. I can turn my fans all the way off, or wide open. I believe there is a 1.25 voltage drop, but in all actuality, it doesn't seem to make much difference. They might not be spinning at the top of their lungs, but almost. I also have not incorporated an On/Off switch, I couldn't see the need for it in my situation. That's up to you. My psu has plenty of power to kick everything in at the beginning.

That's about it. Whole project took about 3 hours the first time. I think I could knock one out now in less than an hour. Not only that, it doesn't look totally ghetto, fer a change. heh.....
This is a piece of Terminal Junction Strip I scavenged for a Fan Bus. No big fancy box with a lot of spring clips, but cheap, and highly effective. It's superglued to the little plastic strip that comes with the case to hold the drive bay slide rails, flush, on the bottom of the case...


Mar 13, 2002
Montreal, Quebec
Or if you like to do the 'ghetto mod' and save a lot of dough.

Buy an interior light dimmer switch from a 93 Toyota Tercel.

Then attach as many fans as your PSU can handle.

Check this thread out. HERE


Jul 26, 2003
i just bought a sunbeam reobus instead :) 20watt per channel, eight channel, led light and everything other little thing for 20 bucks, hehe.


Senior Member
Nov 25, 2001
Niagara Falls, Ontario, Canada
Nice project.

Hmmm 27V regulator, so you could connect it between +12v and -12V and adjust from 0-24V :D hehehehehaaaaa wonder how much these babies can take.....

Or I guess you could set up a thermistor in place of the pot and have your own thermo controlled fanbus. Though you'd still prolly want a pot in there for adjustments.

Humm dunno whether it's just this PC/Browser but your piccies seem to be AWOL.


Dec 20, 2004
Hell's Kitchen, NYC
RoadWarrior said:
Hmmm 27V regulator, so you could connect it between +12v and -12V and adjust from 0-24V :D hehehehehaaaaa wonder how much these babies can take.....

I've been meaning to ask this, and since you brought it up.... Where exactly does one access the -12V (line?)? And if something like this was done, how many Watts could such a line supply?


Sep 7, 2003
Warsaw, Poland
MVC said:
I've been meaning to ask this, and since you brought it up.... Where exactly does one access the -12V (line?)? And if something like this was done, how many Watts could such a line supply?

ATX connector, but check max rating for that line - it's pretty low and notice that with double voltage, you get quad power.
It's better to use oscilating voltage booster, so you could get more voltage off molex.

You can find which rail it is with some volt-o-meter or at www.formfactors.org

Hmm, that regulator is interesting...
Last edited:


Dec 20, 2004
Hell's Kitchen, NYC
Thanks Ven0m, much appreciated. I'm going to have to check out how many Watts a setup like that could handle--I don't have a current use for the knowledge, but ya never know. Thanks, again.