4 pin PWM fan to 2 pin mod?

steveoz · 5 Jul 2016 at 13:55

Hi Guys,

Maybe I am stupid, but I figured connecting red and black on a 4 pin PWM fan would make it just spin at full speed, but it does nothing.

I've googled and I can't find anything useful. All I find is people trying to do the opposite, IE fit a 4 pin fan on a 3 pin header, or 2 pin fan on a four pin header.

Any ideas?

What can I do to get the damn thing to spin up?

Ta,

BuToNz · 5 Jul 2016 at 16:36

What kind of motherboard has a 2 pin fan header? Am I missing something?

steveoz · 5 Jul 2016 at 16:50

BuToNz said:
What kind of motherboard has a 2 pin fan header? Am I missing something?

None as far as I know why?

steveoz · 5 Jul 2016 at 17:17

Ahh right gotcha, I don't have a 2 pin header, never seen one. I was trying to make a 120mm 4 pin PWM fan run on a molex connector, IE, ground and 12v skip the other two. But it doesn't work. I got fed up and ran over the road to Maplins and bought a sickleflow as I was too impatient to order another online and annoyed with playing with it lol.

Tealc · 5 Jul 2016 at 17:33

steveoz said:
... I figured connecting red and black on a 4 pin PWM fan would make it just spin at full speed...

It should and would. The only caveats are that you make sure you are connecting it to the correct 2 pins, and that the polarity of your power source is aligned correctly with the fan. A 4 pin fan is essentially a 2/3 pin fan with additional circuitry to switch the fan on and off several thousand times a second.

If you were to connect 12v to the PWM and tach line instead of 12v and ground then the fan wouldn't spin, hence why I thought to mention it.

steveoz · 5 Jul 2016 at 17:51

Tealc said:
It should and would. The only caveats are that you make sure you are connecting it to the correct 2 pins, and that the polarity of your power source is aligned correctly with the fan. A 4 pin fan is essentially a 2/3 pin fan with additional circuitry to switch the fan on and off several thousand times a second.

If you were to connect 12v to the PWM and tach line instead of 12v and ground then the fan wouldn't spin, hence why I thought to mention it.

Thanks for the reply. The fan's back in it's box now as I got impatient and bought another.

I did wonder, I couldn't see any markings on the fan and all the wires were black. Generally speaking the first pin is normally ground, then 12v next to it which I tried on this fan but nothing :/