Asus stated on the oficial release topic (
https://rog.asus.com/forum/showthread.php?32906-ASUS-UEFI-vBIOS-tool-for-GTX-600-series-cards!-It-s-...) that they will only support their own motherboards because they have tested their hybrid BIOS/UEFI firmware on their own boards.
This guy created a patched tool that should get you going.
http://rog.asus.com/forum/showthread.php?36689-Patched-ASUS-UEFI-vBIOS-tool-for-GTX-600-series-cards!
Use at your own risk. Read all info carefully before you do something.
By what I have read, their hybrid firmware seems to work well with boards that were not Asus made.