I think I didn't get you.
I already did a PRAM reset without success. What I'm trying to know is what-the-h*ll version of vBios I have to flash in this card and where do I find it.
As said, with General, High Sierra doesn't boot at all (and I have to maintain this version till I'm sure the OCLP Monterey is fully functional). I read somewhere that the Device ID 0x6640 is known to High Sierra and associated to AMD Radeon R9 M380 card, so now it's using this driver. I should change the ID to 0x6646, but can't find the right vBIOS.
Btw, the installation of Monterey on 2nd SSD was done by the book. First with USB installation, then installation on SSD then post install root patch.
What am I missing?