Woohoo successfully flashed bios modded with AMIBCP. Had to use an older version of Efiflash. Also noticed it took a little bit to enter the BIOS, but I have the option now. Link to older Efiflash https://www.sendspace.com/file/z0oove
EDIT: Successfully booted into El Capitan setup on USB flash drive. See's the USB 3.0 ports and SATA. The USB 2.0/1.1 ports aren't working yet.
Bravo. Which version of the tool did you use to modify?
I think I found safe way without modifying BIOS on gigabyte motherboards. Use "Save Profiles option," edit the save file and then load it. I believe this saves all settings in a certain format, even ones not shown in bios.