# 4 pin fan with 3 pin fan controller need help



## HiFiFun10 (May 9, 2020)

I have a 3 pin fan controller and I want to use my 4 pin fan with it. I want to be able to see rpm and also control the rpm with my controller.

My fan is powered by my psu because my fan controller does not have enough Watts to run my 12 watt fan. I am currently using the black and red wire. I have 2 wires which are sensor and PWM which I am not using and need help with, maybe I can hook it up to my fan controller?.

I have extra fan cables for the wiring and I hope some one can help me. I want to mention again that my fan controller supports 3 pin and not 4 pin.


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## FreedomEclipse (May 9, 2020)

Basically this








You want to pop out the yellow cable and split it off to its own header. You can plug that end into the motherboard for fan RPM while still using the ground and +12v cables to power the fan from the controller.

Normally theres a blue cable that goes to the PWM controller on fan - Just ignore that. you can use a pin to pop it out of the header and tuck it away. usually fan with fan controllers especially dumb ones that have no display and just knobs to turn speeds up and down. the 3rd pin is usually a dud meaning it isnt connected to anything - in some cases a 3d pin isnt included at all.







So you'll have two connections. yellow cable for the motherboard and the other for rpm control. study the pin diagrams to make sure you dont mess up

You'll need a 3pin female fan connector..






you can pick up one of these at an electronics component store or rip one off an old or dead fan


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## Fry178 (May 9, 2020)

do you really need to know the rpm? fans work fine without it, same for any controller. 
to do a "profile" for the fan (board/controller) just go by noise, and have fan max setting little below max allowed (cont) temp. 
either way, nothing requires the rpm for that, and what good is, as cooling/noise is more important than knowing what rpm the fan is doing..


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## HiFiFun10 (May 10, 2020)

FreedomEclipse said:


> Basically this
> 
> 
> 
> ...



My extra fan wire has 3 wires black, red, yellow. Which wire goes into which color?. The wires I have not used are the tachometer sensor and PWM. 

I am going to try tachometer which is yellow to the extra fan 3 pin yellow wire. I don't know if I need PWM.

More help would be great.

Also rpm display is good I would like to be able to see the fans rpm speed.


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## FreedomEclipse (May 10, 2020)

HiFiFun10 said:


> My extra fan wire has 3 wires black, red, yellow. Which wire goes into which color?.



I dont understand your question.

Basically just copy the pictures/diagrams provided except only for the yellow wire. your 3 pin to the fan controller will become a two pin (B&R) Yellow gets split to a different plug that goes to the mobo for the fan speeds.


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## Fry178 (May 10, 2020)

@HiFiFun10
pwm has nothing to do with wire itself, just how the fan is controlled (DC= variable voltage between 4-12V, PWM constant 12V that gets turned on/off depending what fan speed is required).
sure, its nice to have, but will not have any impact if you dont.
paying attention to temps is more important.


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## HiFiFun10 (May 10, 2020)

Fry178 said:


> @HiFiFun10
> pwm has nothing to do with wire itself, just how the fan is controlled (DC= variable voltage between 4-12V, PWM constant 12V that gets turned on/off depending what fan speed is required).
> sure, its nice to have, but will not have any impact if you dont.
> paying attention to temps is more important.



Do I just use the tachometer sensor wire which is yellow and rewire it to my extra 3 pin which has 3 wires?.

I was going to use the yellow wire with the yellow wire on my extra 3 pin which is the tachometer wires. Then plug it in to my fan controller with only the tachometer wire connected and leave the black and red not used because I have my fan powered by my psu?.

My extra 3 pin wire is colored like this, black for ground, red which is voltage power and yellow which is the tachometer wire.

Any idea?.


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## FreedomEclipse (May 10, 2020)

HiFiFun10 said:


> Do I just use the tachometer sensor wire which is yellow and rewire it to my extra 3 pin which has 3 wires?.



the extra is supposed to have NO wires apart from the yellow one which you split from the main one.


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## John Naylor (May 10, 2020)

I don't see the point... you can read the RPM by splitting off the correct wire ... but it is still going to run at max speed if powered by the PSU   And as you said, your controller doesn't have enough wattage capability to handle that fan. 

There are fan hubs (i.e Phanteks) that will allow the MoBo to control speed of 3 or 4 pin fans pin fans.  With 3 pn fans, I typically gang 4 - 6 fans together and connect them to a MoBo header.  Most headers top out at 1 amp or 12 watts.  with (6) 0.14 amp, 140mm, 1250 rpm fDCV ans on each hub / header Im well under the limit.  With PWM fans, you use an auxillary SATA power cable to provide the power and can then connect up to 12 fans....  (30 watts IIRC) ... speed control still comes from the MoBo header.  Only 1 of the hubs fan connectors send a rpm signal back to the MoBo.






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