MSI Z87-G41 PC Mate refuses to boot from USB

I am currently trying to update my old system by reinstalling macOS.

The system is running Mojave on the following hardware:

  • MSI Z87-G41 PC Mate (Haswell)
  • i5-4750k
  • 12GB DDR3
  • 256GB SSD
  • NVidia GTX 760

The PC however refuses to boot from USB, and even when I boot into my SSD OpenCore and then select the external USB EFI it just reboots into the internal OpenCore. It seems to be related to the BIOS settings but I cant quite put my finger on it. Tried different usb drives, all ports and even changing BIOS settings. Its currently in UEFI+Legacy Mode, which lets me boot from the internal. Switching to Windows 8 / 8.1 mode does not let me boot from either. (Seems like this is not supposed to be switched on).

Does anyone have some information about this very special problem?

submitted by /u/Killuminati91
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