I didn't want to re-write the hybrid UEFI, so I picked the legacy side... which also has a UEFI that you are unlikely to use. The firmware I posted was my card's legacy BIOS + Mac EBC EFI. I left mine in legacy out-of-box, but it probably works either way OOTB without flashing. Should be good! You won't get 5.0 GT/s link speed until you remove the resistor mentioned previously though.