How to tell if CPU fan is PWM

[acordeon]

How do i tell if a CPU fan or a case fan is PWM vs voltage controlled? Is it just whether it has a 3 pin plug vs a 4-pin? Are all 4-pin fans PWM?

I ask because I installed the stock Wraith Stealth cooler for a Ryzen 3 chip, and I can't find specs for it anywhere, and don't know if it's PWM or not. It's set to PWM in the BIOS now, but it's running at a high RPM even though my CPU temps are cool. So wondering if it's not actually PWM.

 

[lumineZ]

3-pin = not PWM
4-pin = PWM

Here is the kicker ^^

4-pin with only 3 cables = not PWM


The Wraith cooler fan is PWM. You have to set a fan curve using a program. All motherboard manufacturers has it.
Some motherboards also has the fan in a DC mode and not PWM, this you also have to set in bios then if this is the case.

Set PWM fan speed according to CPU temp.

 

[acordeon]

Thanks!