Well, mine was a epic tale of woe that seems to be unique. So, take what I say with that in mind - odds are you will not encounter the same issues.
I received my first Asus X99-S with the Corsair Vengeance 2666 16gb and the 5930k. Set it all up and booted up. Everything hunky dory, except BIOS only reporting 2 sticks of ram. Tried a number of things to fix that which all culminated in deciding that I needed to re-install windows.
Re-installed windows and it got to the point where you set it all up (you know, choose the theme, add the default account etc) and the mouse and keyboard stopped responding. No USB ports allowed them to work. No mouse or keyboard combination worked. So had to abandon that install and attempt it again. Obviously, the disk I used was now locked so had to use a new one. Started the install process and after the first reboot, nothing came up. System wouldn't even POST.
Started to diagnose that, right to the point of actually buying a new PSU to remove that possibility. All to no avail. So RMA'd the CPU and Mobo (I was convinced that the RAM was fine, maybe it wasn't...).
A week later and, with the mobo determined to be the DOA component, had new mobo and original 5930k returned. Built the system and then the system wouldn't POST at all (but the lights all came on). Did the same set of triage to figure out the problems and it pointed at the mobo again. This time I RMA'd the whole lot, mobo, cpu and RAM, got them all back, built the system, installed windows and everything it now working perfectly!
...
Well, apart from the mouse randomly stopping working ... and the screen sometimes flickering
Total time from first purchase to working system == 6 weeks