I tried to mod bios but now Windows does BSOD when installing blockchain drivers.
Try installing the latest 17.12.2 Adrenalin drivers. After it installed you can set the Compute mode in the settings.
Radeon settings -> Gaming -> Global settings -> Per GPU - Compute mode
Also how did you mod? Did you download the BIOS from your card and edit that? Could be that the changes are too high for your card and when it initialises it crashes.
I restored original ASUS bios to my RX 570 4GB cards, removed drivers totally with DDU, rebooted, installed Adrenalin 17.12.2 drivers, rebooted, switched to compute mode, updated Claymore to v10.4 and now I got 16MH/s Ethereum speed per card

What next?