I have same variant and is in my most under performing rig compared to Sapphire version of RX 570. I downloaded all possible Bios files from anorach tech as modifying it with PBE wouldn't work strangely.
your ways to modification your GPU bios less precise. every card has a different bios version. if you're using downloaded 'mod bios' from somewhere that didn't use the original bios of your card.
it will make your system unstable and may damage your card. you can do standard mod bios using newest of PBE with one click, and the rest key is tune it with the right settings, will be safer.