Hello,
I’ve used the guide you linked as a backup for flashing in case something went wrong. However, I mainly used the AFUWinx64 flashing method and it worked flawlessly with me.
You can find the link for the program in my first post, and the guide to use it here:
Edit: read your edit, I’ve ran mine on 4.7Ghz for a while during fall/winter untily cpu thermal throttled and reverted back to 4.6Ghz.
It unfortunately will only run with 24GB of ram, and 32GB will give you an error. The main reason is that the bios will require further patching to support 32GB, and I have no experience in doing any of that.
As for the M.2, I don’t have one installed, so I dunno.
Also, expect to have few beeps during boot. Keyboard and mouse(USB) are not detected after you enable 4G decoding and turning off CSM