I looked at the manual for your board and the BIOS part of it does not say EFI or UEFI. I also did a search and found the following which says your motherboard does not support UEFI:
https://vip.asus.com/forum/view.aspx?id=20111121044711678&board_id=1&model=M5A78L%2FUSB3&page=1&SLanguage=en-us