View Full Version : Fan Speed??

01-01-02, 06:01 PM
I have a 7000rpm fan on my CPU, I'm 19 and live with my parents, most nights I like to stay up till the early hours , however my parents want to sleep and complain about the noise from my fans.

What I want to do is slow my fan down to about 5000rpm at night. Does anyone know of an easy way to do this?? I have seen fanbus guides and they all look like too much hard work and I'm not very good with electronics??


01-01-02, 06:51 PM
what heatsink the sk6? if its not the sk6 get a 60 to 80mm fan adapter and a lower rpm fan

01-02-02, 01:00 PM
It's the FOP heatsink i.e. Globalwin FOP38. I like my 7000rpm too much to take it off and when I overclock usually for benchmarking etc, I set my bus speed to around 155FSB, so I need it in there to keep those temps down.

I have looked into the matter a little more and it seems the thing I need is a reohstat anyone had experence building one of these or knows where i can find a guide on making one???


01-02-02, 01:59 PM
does ur fan have a 4-pin or 3-pin connector?

01-02-02, 02:15 PM

can wire it like this,need to know how to solder.bought the rheostat from radio shack for like $3.
need to know the wattage of the fan.

01-02-02, 02:56 PM
YOU DO NOT NEED THAT HARDWARE CRAP!!! There's a little program that you can use to control EVERY fan connected to the motherboard. May not work on all mobos though.


01-03-02, 03:37 PM
Pu on a 60mm GlobalWin 5200rpm fan. With my new program vcool with no overclocking at Idle my CPU temp is around 35.C which is great and is exactly the same as the temp with the 7000rpm fan. However when Overclocking I obviously did see a better perfromance from the 7000rpm but as I have no need to permently overclock at this time so I'm happy.... for now. :D

BTW. That the software fan controller didn't work on my mobo but thnx for the link. And thankz for the reohstat tips I'm going to build one just for the fun of it when I find some free time. :p

01-03-02, 04:02 PM
It worked for me by changing "Speed 2" down.

01-03-02, 05:27 PM
I tried it again and found that if I moved the speed down to 0% the fans turned off but if I moved it to 50% then the fan speed were displayed as being the same however they were in fact slowing down.

So when tommorow I'll put the 7000rpm back in and run it at 5400rpm speed until I need it to go any faster. Will running the fan at a lower speed damage the motor at all??

01-03-02, 07:28 PM
I don't think so as it's just changing the voltage levels.

01-03-02, 08:05 PM
it wont damage the motor.

01-03-02, 08:25 PM

Why did you wire the fan like that?
You are using the 5 volt line and dropping the whole supply voltage across the pot. The way you have it you will only be able to vary from five to zero volts and you are dropping the whole supply voltage across the pot to ground. That will burn up the pot, unless it's high impedance.

Here's a pic of how I would do it. You only need two of the terminals on the pot, and I would use the yellow wire which is twelve volts. Then you can vary the voltage from zero to twelve volts.


Please explain your set-up to me, I may be overlooking something here.

01-03-02, 08:34 PM
Here's a link (http://bit-tech.net/article/56/) to what I'm talking about.


01-04-02, 08:36 PM

This is what I'm tring to explain to you in the PM. You have the supply voltage going to ground through the pot. If the impedence of the pot is not high enough you will burn it up. You have the pot wired right for an audio volume application. Also keep in mind if that fan is 12 volts it will never get to full speed. The red wire in a PC power supply is 5 volts, the yellow wire is 12 volts. I don't know what voltage that fan you have requires.

Usually, but not always, pots are wired such that turning the control clockwise gives more effect. The diagram below represents a volume or gain control. In this case, rotating the control clockwise increases the resistance between the output and earth, so more of the input signal is sent on to the next stage. You might sometimes see lug 3 called the "hot" side of the pot and lug 1 called the "cold" or "earthy" side. Lug 2 is the wiper connection. This applies to linear and log (audio) taper pots; reverse log taper pots are available, but are not commonly used in effects circuits - the only examples I can think of are in the Octavia and Univibe.

http://www.green-fuz.freeserve.co.uk/effects/pot.gif http://www.green-fuz.freeserve.co.uk/effects/pot.gif

The way you are wiring it you will drop the entire 5 volts across the pot to ground (pins 3 and 1 in the diagram) Some PC power supplies have as much as 30 amps on the 5 volt (red wire) circuit.

What is the value of the pot that you are using?

Do you remember ohm's law?


I'm just trying to go over this with you because I'm getting ready to do a fan mod simular to yours, and I want to know which way is best myself. :2cool:

01-04-02, 08:54 PM
ok i see now.

i didnt mean to use the 5v line.:(

i member ohms law.

that pot is a 25 ohm,should be fine for a fan that uses 7W.

thanks roundeye ;)

01-11-02, 11:35 AM
I built a reohstat today, the simple but effective guide at bit tech made it real easy, and it works perfectly. Put a Blue Orb cooler on my North Bridge aswell, Now I need to find some time to drill a hole somewhere in my case for the reohstat :confused: ....The modding very slowly continues. http://forums.bit-tech.net/images/smilies/cool.gif