Just seeing this now…
So been through minerstat and windows 10 OS…
With hand full of motherboard over the last few months…
only things that truly matter are listed below
4 g decoding = enabled
csm = disabled
all PCIe ports speeds are set to 2.0 or 1.0.
asrock settings that work for me are in pictures
For all testing of booting issues, I would use windows. once you can get windows to reconize your cards with bios settings, or at least past post boot then move on to other OSs.
Also Always plug your video connection to ever card. The display might be on one of the other cards; depending on your motherboard, lol.