Thats a lot of problems for a very nice build. The RAM is reading low probably because you did not set it in the BIOS.
But for the other things, I'm wanting to blame the motherboard. I had an ASUS Maximus III that had similar issues for over a year:
glitchy ethernet port, over 1000ms ping most of the time
unpredictable hard drive controller (finally what killed the board)
among other things
At the time I was a noob so I figured most of it was normal, and didn't really realize what was going on. If possible I would seriously consider RMAing the motherboard to the store you bought it.
If you wait too long your be stuck with ASUS support, its been 9 months for me and they haven't replaced my board. Between sending me one with bent pins then asking me to pay to replace it, and ignoring me for many months at a time then emailing me back like it was just yesterday I emailed them I still have a junk board.
Besides the motherboard I would say the PSU, hard drive, or RAM could be behind the issue. Everything in your build is screaming high quality though so there is nothing too obvious sticking out that I haven't said above.
I used to be proud to be an audiophile, but when you go from "isn't $50 a bit much for a headphone" to "cool, only a few hundred" and you start selling off parts of your PC to get your next fix... oh well. It's still cheaper than being a car guy.