Mother Board fan headers

[WesleyT2]

My Mother board has 2 CPU 4 pin fan headers and 3 system fan headers I'm only using one cpu fan header is it possible for me to use one as a a regular fan header?
My mother board is a MSI Z170-A PRO https://www.msi.com/Motherboard/Z170-A-PRO.html#hero-specification

 

[Justiceinacan]

You could but if your CPU's getting hot, that particular fan's RPMs are gonna skyrocket for instance. Basically RPM is dictated based on temperature.

Edit ; by the looks it says CPU_OPT which iirc means that's intended for radiators. Forget if the function is changed in any way but there's a chance it might not play nice with fans, or it was intended for a dual fan CPU heatsink.