The latest BIOS Update from ASUS is 3305 (from 26/07/12) and for me It was unable to save most BIOS changes. So Is there a way to Flashback/Downgrade the BIOS of the ASUS Maximus IV Gene-z/Gen3 from 3305 to 0402? I did hear that many ways didn't work. So I am asking here, to perhaps find hope in doing so.
According to the manual for your board (chapter 3-46), it should be possible. Either use the disc that came with the board or a USB drive loaded with your choice of available BIOS versions. Trying it may be the only way to see if it really works.