@Krakatoa Yes, Windows 8.1 itself is compatible with 32bit EFI. There is another EFI bootloader (bootia32.efi) in x86 iso images. So you can also build an iso that supports both UEFI and BIOS with the same oscdimg command-line. I don't know which PC main board actually supports booting UEFI in 32bit mode but I believe most of the main stream mother boards are incapable of it.