Hi wildwillow!
I really appreciate this post, you were very elaborate, but for me it could not have been elaborate enough.
I decided to start my first hackintosh based on your components and your guide, much appreciated! I did it almost the same as yours, but with a GTX770 and then a TitanX and two Samsung 950PRO's (one win, one mac, so i needed to get the kext for those). I wanted to thank you for this guide as I am running very smooth. I also have a Mac Pro Trashcan, and needed expandability. Damn this device nails it, the samsung 950 pro's are insane, >>1000mb/s RW.
Regarding the standoff screws you didn't have, there were 2x sets in the motherboard box with me.
Stability is just 100.0%. Been throwing at it everything i can for a week now. I predict hackintoshes might get a more popular..
So get that Samsung 950 Pro because of this: