Also here I leave my grain of sand, these are timing that I found by chance in the forum and implanted it in the vbios (they are slow timing) maybe it can be useful for someone
https://www109.zippyshare.com/v/my2xJZr0/file.html <------ It has a minimum voltage of 775 mv so there is a large margin for undervolting PD, disclaimer, I am not responsible for the damage caused although the changes are very minimal compared to the original bios, it applies only to the nitro version of sapphire
PD2, in case of failure these cards have dual bios, change to the main one and repair the secondary bios with a previously made backup
What the hashrate for etchash and kawpow with your bios?