Motherboards with 4 pin PWM (System) Fan Headers?

[Operandi]

So I want to order the parts for a new build and looking at the motherboards, and all of the AMD 870 boards I'm looking have a 4 pin PWM header for the main system fan. I'm but unsure if I need PWM fans dose anyone have experience with boards like this?

I downloaded the manual for both Asus and Gigabyte boards I'm looking at and the Asus board makes no mention of how the system fan header functions and the Gigabyte shows the 4th pin which would be for the PWM as "reserve".

 

[mfenn]

You can use a non-PWM fan if you wish. Every BIOS (except for Dell, HP, etc.) that I've seen allows you to fall back to voltage control.