Windows 10 on PCIE SSD in a flashed 4,1

[Agfa]

I've been trying to figure out the specifics of this for several days, and I know at this point that I can't do bootcamp normally due to the SSD being seen as external by macOS, and I need to do an EFI install of windows, but I can't find instruction on how to do that for my particular setup. The main things I can't seem to find are:

1. What version of the windows iso do I need, and do I make a dvd or usb installation media, and any specifics around the creation of the media?
2. How exactly do I need to perform the install, I've read about needing to use dispart at the beginning of the installer to setup the target drive?
3. What version (if any) of the bootcamp drivers should I use once windows is installed, and what individual drivers should be installed?

macOS is currently booting off a 128gb apfs partition on a 256gb AHCI sm951, and I also have a 128gb SSUAX apple ssd. Ideally macOS, windows, and linux could have ~128gb each. I have an EFI graphics card and I want to be able to use refind on a separate hfs+ volume on whatever disk macOS ends up on, so the "startup disk" function in the bootcamp software isn't crucial.

I'm trying to do a lot with this old machine and my knowledge of the deeper workings of EFI systems is very limited, so thank you for any help you can provide.

-Griffin

Specs:

Hardware:

Apple SSD

sm951:

 

[tsialex]

First step is to upgrade your firmware to at least 140.0.0.0.0, it has native NVMe boot support and Apple improved boot ability. I wrote a sticky thread about what you have to do to install Mojave, there you will find the instructions on how to upgrade your BootROM, read and upgrade your Mac to 14x.0.0.0.0.
https://forums.macrumors.com/threads/mp5-1-what-you-have-to-do-to-upgrade-to-mojave.2142418/


Some people got Windows UEFI installs working with 1809 and 141.0.0.0.0, but this causes problems since MP5,1 is a EFI Mac and Windows don’t differentiate it from UEFI Macs, causing NVRAM problems. Long story short, if you can install with CSM, do it. If you can’t 141.0.0.0.0 and 1809 are the starting point.