Is this a pwn header?

[Bone9]

I've got a 4 pin pwm fan connected to the cpu_opt header and I can control the speed in speedfan but it makes a ticking noise and wont start to spin till at 63%

Comparing the socket to the cpu one its voltage controlled isn't it? If so would a 3pin fan tick?

 

[doyll]

Only the CPU fan header is PWM. All others are voltage control.

 

[Bone9]

Thought so, thanks buddy.