I will never be using the built in microphones in my GTR9 Pro and I wanted to disable them for increased privacy (and to free up a few resources). The mics can be disabled in Windows via Device Manager; however Windows updates will automatically re-enable them. A better solution is to disable the mics in the BIOS.
After some trial and error, I discovered that the built in microphones can be disabled via:
BIOS -> Advanced -> AMD CBS -> FCH Common Options -> USB Configuration Options ->
USB0 2.0 port enable -> USB0 2.0 Port 3 -> Disabled -> F4 -> Y
This method will disable the microphones regardless of operating system. I do not know if this method works with the original (Intel NIC) version of the GTR9 Pro.
I hope this information is of use to others.
