New
#11
Make sure you are looking at the right docs there is several variants of this board not all of them are PWM capable. It will be a edge case where its easier to manufacturer 4 pins and just slap those on the non PWM compliment boards this is common on electronic goods because it saves production nuances.
I am looking at docs right now for this board that don't have PWM fan headers. I guess it depends on your exact variant.
- - - Updated - - -
Cpu And Chassis Fan Connectors (4-Pin Cpu_Fan, And 4-Pin Cha_Fan1/2); Internal Connectors - Asus M5A97 Manual [Page 23] | ManualsLib
- - - Updated - - -
I mean its either you don't have a R2 variant or there is inconstancy between your add-on PWM device and the MB's controller.
You sound like you know what you have but its not uncommon for people to overlook nuance.