I know this is a long shot but a few things to try. Check make sure you have the latest bios a07. Try to run as administrator when installing. if that don't work try and see if you can do it in safe mode.
1. I dont mess with my bios. 2. I install the drivers only in administrator. 3. I dont think Safe mode will help
maybe an inf driver tweak ?? i had to declare a new vendor id and pid line, to make a driver work under win 8.1 ...
I think in the windows 8.1 pro version the driver were loaded, but im not sure.. Edit: windows 8.1 pro video driver installation 14.2 dont seem to work