Guidance by thread date, starting X79 to X99:
[Guide] - How to Bifurcate a PCI-E slot - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum
[Guide] PCIe Bifurcation - mapping IIO/IOU to PCIe slot - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum
[Guide] Adding Bifurcation Support to ASUS X79 UEFI BIOS - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum