Ngreedia blocked BIOS flashing from the Pascal generation onwards. You're out of luck unless you're willing to spend
weeks reverse-engineering the BIOS dump. Trust me, I went down the rabbit hole to try to overclock my Tesla P100 cards by 30% in order to get 50 Mh on ETH.
Older Ngreedia video cards like the GTX 1060 3GB used to have this issue, too, where most got 22 Mh while others with Micron memory were 18 Mh.