ASUS rolled out an optional video BIOS update for its GeForce GTX 680 graphics cards, which lends them GOP UEFI support, letting users take advantage of "Ultra Fast Boot" and "CSM disable" features. To use Windows 8 Secure Boot feature as intended, it's not enough that your PC motherboard supports UEFI, discrete graphics cards should support GOP (graphics output protocol) UEFI, as well. Very few graphics cards at the moment support it, and graphics card board vendors are making efforts on their side to add it.

ASUS' GOP UEFI VBIOS update ships as an executable that updates VBIOS from within Windows (provided it's being run with Administrator rights). ASUS tested the update only on its motherboards. Also, once updated to the UEFI-hybrid VBIOS, the graphics card can't be flashed back to the older legacy one. Risk takers can find the update here. Find more technical information at the source.