I had issues with a new built with Fatal1ty X299 Gaming XE. It would not post for more than 1 sec and nothing more. Q codes of A2, A6(Ab), A9. Did everything in the book, boarded on box, reset cpu, RAM in different slots, with GPU and without, clear CMOS all different ways. This went on for 3 days, and many hours. Found a post somewhere on a different board saying that (for that issue) that HDMI would work but not the Displayport. Sure enough, I connect the HDMI only and I was able to see the post and do what I had to do. I was then able to do a Windows installation (this is a new build) and download GPU driver. Now I can connect the DP.