A very key component is the speed of memory along with the type of memory and the memory controller. Get DDR4 and as fast as you can. That's incredibly important in realtime applications, especially under load.
 
 
 

What are recommended x99 motherboards for DAW for the 5820?
Are USB 3.1, Thunderbolt, and/or m.2 connections necessary? If so, in what scenarios?
 
Thanks so much!

I like the ASUS X99 Delxue, that's the one I got. It works well and has nice low latency.
 
USB 3.1 is a non-issue at this point. Nothing uses it, and as a practical matter USB 3 is only used for audio interfaces with a ton of channels like RME's MADI stuff. USB 2 is all that's needed for normal audio interfaces.
 
Thunderbolt is not needed unless you want to use a thunderbolt interface. The problem with that is that many of them only have Mac drivers so even if you had a TB port, you couldn't use it on your system.
 
M.2 can be useful if you want to get a really fast M.2 SSD. That is more of a "because I can" thing than really useful though. I have one, a Samsung XP941, and it really offers no noticeable real world benefit over the 840 Pro it replaced despite having much higher benchmarks. Also M.2 is just a small PCIe 4x connector, so you can always add it via a cheap addon card.

Sycraft,
 
Thanks so much for the info. VERY helpful and clear.
I decided to go a different direction... Following Jim R.'s and other's guidance, realizing a 4790 with mature z97 mobo will be fine for audio needs, and a doubling of my current speed. I decided to pursue an upgrade rather than a new build. I'll be able to use most of my existing gear. 
 
Thanks again.
Craig
 

Jim Roseberry
Ideally, you want fast clock-speed *and* more cores.
You really don't want to sacrifice one for the other.
(If it's a large difference in clock-speed, I'd go with fewer cores running significantly faster.)
 
The 6700k is barely hitting the street.
I'd sit out the first gen motherboards... and let the issues settle.
 
You'd be very pleased with a six-core 5820k running at 4-4.5GHz.  
 

I've been researching this very thing myself lately, and since I've never build my own PC, I'm a little overwhelmed with all of the options. I'm considering getting a custom build from you, Jim. I had a question though.

Does StudioCat ship to Japan? I tried to contact you via your support page on your site, but I never got a reply. I figured I'd seen you pretty active on these forums, so I thought I'd reach out here. 

Sorry for (kind of) hijacking the thread, RedSkyRoad!