Everything you see in the posts is all I did and it's been rock solid. More so than my GA-Z270X Ultra Gaming.Slick build. I managed to get everything up and running. I keep facing sudden reboots, even with the same motherboard and CPU as you. Were those BIOS changes the only thing you did?
Use 18,1 as 19,1 requires a special build of 10.14.4.