OK, few things. I think the reason why I don't see the BIOS screen at boot up is because my display port cable is plugged in. When I plunged in a HDMI cable, I saw the in screen. Weird. Mind you for now my 5700 GPU is on my other machine, and I won't have access too for a little while.
For your EFI, all the BIOS settings (per guide) are set, and I see Windows and macOS. When selecting the macOS (after a NVRAM reset), its timing out. I think that's just because I have no ATI GPU installed, just a Nvida GTX 1070. I was hoping to boot without graphics card to just try audio on macOS for starters!!! If you have a solution, let me know!!
I think it may be best to report in when I can test with my 5700 GPU next to the AMD CPU machine.
FYI. For audio on Windows this has been insanely good so far. I've been loading Steven Slate 5 drums and accent drums loading full kits on my edrums playing them with a 32 buffer using a rme ufx+. NO GLITCHES after extensive playing.
I want to under clock to see if it helps VI plugins or Pro Ttools load but so far we are rocking.
I've tested all the TB2 - to TB3 adapters as well on Windows.....akiko StarTech and Apple, and THEY ALL Work!
My temps are like 45-60 in core temp with a Be-Quiet 500 case, and the dual fan Dark Rock Pro heatsink.
...Like I said. I just worry about no dual BIOS in case something craps out hard.