[SOLVED] How do I manage 3 pin fan speed?

[opprerson]

Hi I have 6 x 3 pin molex fans is there a way control their speed? I have a Asus Prime Z490 motherboard.

 

[Dj0gany]

Nope,you need a PWM fan,the one with 4 pins.
Your 3pin will run on full speed all the time,just like mine 🙁

 

[Phaaze88]

To control 3pin fans in a board like that, you need to be able to control the voltage being fed to them. It doesn't work in the same manner as PWM.
If you go into bios, and set the fan header controls to DC Mode, does it then let you control the voltage - 12v, 7v, 5v? If not, you are going to need a device, like this one, that restricts the voltage going to the fans.
The one I linked cuts it to 7v, so about half speed.

 

[Paperdoc]

I am not clear what you mean by 3-pin Molex fans. Do these fans have a cable with THREE wires that ends in a common female fan connector with 3 holes? Or, do they have a larger 4-pin Molex connector with 4 PINS inside a shroud? Or, do they have one of each of these on a shared cable? Something else?

Assuming they are 3-pin fans, there IS a good way to control their speeds with your mobo headers, but first we need to know the max CURRENT in AMPS each fan can use. Sometimes that is on the fan label, or maybe it will state WATTS instead of amps. If you can't find either of those, can you tell us the maker and exact model number on the fans. Maybe we can look them up and get the specs. With that we can advise precisely how to do it.