Nov 18, 2013 4:59 PM
When you enable Secure Boot, the BIOS must have UEFI drivers for all necessary hardware in order to support the use of this hardware during the boot process. The BIOS provides the drivers for the embedded features, including Intel graphics, but add-in cards, to be included, must provide their own UEFI driver (via OP-ROM). The authentication failure message is an indicator that the OP-ROM provided on the graphics card is not in compliance and/or does not provide the necessary UEFI driver. Look to the board's manufacturer for an updated OP-ROM that brings it into compliance...
This was the case for me. I was able to find a way to update my video card BIOS for UEFI and all was well.
For my ASUS card without an ASUS board I went here: