Going back to optimized defaults did not fix the problem. However, moving the network card to a different PCI-e port did? Seems like both of the 1x slots on the bottom were causing issues with my ASUS PCE-AC66 card that caused the freezing on the loading screen. Is this something you guys can look into?

I have it in one of the X16 slots now and it boots up all the time. The one lockup I had was from clocking too high again afterwards.