The OP user never log since his post request and our GURU is retired.
What revision you have: GA-970A-D3 rev. 3.0 - 1.3 - 1.2 - 1.0/1.1 (3.0 UEFI, others Legacy) and the following method is not supported.
Why dont you try it yourself using our guide here (ONLY for rev 3.0):
[HowTo] Get full NVMe Support for all Systems with an AMI UEFI BIOS - Special Topics / NVMe Support for old Systems - Win-Raid Forum (level1techs.com)