Try disabling UEFI and olso do those:
- if not all gpus are working try changing PCI GEN to 2 or 1 or AUTO
- make integrated GPU as default
- upgrade bios to newest or not

- Use a Skylake processor
- enable 4G decoding
If non of those will help and also none from those images helps then i really have no idea

Tytanick,
I just wanted to confirm that I am still able to to boot smOS with above 4G decoding enabled on two separate MSI z170a M5 mobos.
To those of you having problems, are you running the Beta kernel (4.11rc3)?
Are you SURE you have downloaded and successfully installed MSI's updated bios (1.D)?
If you haven't updated the BIOS to 1.D, you will not be able to get it to boot properly with the board fully loaded with cards without doing some hacking on the BIOS.