Do 4 pin Sys fan headers control PWM fans?

[DTWD]

In other words, will my motherboard stop a PWM fan if the system isn't hot enough?

The reason I ask is that the fan spins up on boot but then spins down and just rocks occasionally. If I plug it into a connector off the PSU (via an adapter) it spins all the time.

 

[DTWD]

Hmm any ideas how I go about testing this?

It's defo a PWM fan.

The motherboard is a GB z68xp ud3

 

[DTWD]

Cheers.

I have it running constantly using the PSU connection at the moment.

It's quite enough that I am happy to leave it. When I see a fan controller I like I might grab one.