@Apolo7: I don't know what Z-170-A manual you were reading, because mine doesn't have a page 55. It has a 2-55, not a 1-55, and I don't see the VT-D setting anywhere in the book. So maybe you were reading some other motherboard manual's book. An actual answer/fix would have been MUCH more helpful (if you ever had it) than spouting off some page number.