Can someone help me figure this out? I'm running running an iMac 17,1 smbios with my GTX 1080 and all I get is a black screen on boot. I know SIP is disabled via csrutil status, I know the graphicspolicy.kext config for the iMac 17,1 board ID is set to none via the many various methods of the AGDP fix, and I know I have my primary graphics output set to PCI-E in the UEFI bios. Yet it's still a black screen on boot.
i7-6700k
ASUS ROG Maximus VIII Extreme motherboard
64GB Corsair Vengeance 3200Mhz
EVGA GTX 1080 Superclocked with ACX Cooling
Corsair AX860i PSU
Samsung 850 Pro SSD
6TB Western Digital Black 7200rpm HDD