I assume you updated your BIOS because you said you set 4G encoding and that's missing if you have an old version 
Your bios date should be 3/17 or newer'ish?
Did you set the PCI's to Gen-2? Two locations in that bios...
Don't worry about that PCI error in the device manager. Both of my Asus Prime Z270's show the same thing but both rigs mine fine (one nvidia rig and one amd rig).
Your bios date should be 3/17 or newer'ish?
Did you set the PCI's to Gen-2? Two locations in that bios...
Don't worry about that PCI error in the device manager. Both of my Asus Prime Z270's show the same thing but both rigs mine fine (one nvidia rig and one amd rig).