Asus x99 Strix ROG Gaming
8 dimm slots, 3 video cards (two dual slot), onboard buttons
Xeon E5-2673 v4
20 core / 40 thread
Thermaltake Floe Ring 360
Fits great
Thermaltake 1050 iRGB PSU
Plenty of power
G.Skill DDR4 2666 64GB
Using 4 16GB kits no issues (I know its not officially supported by G.Skill)
ATI Radeon X600
Cheap vid card for Unraid to grab for admin console
EVGA GTX760sc x2
I have one on each VM, one is a Win 10 and other OSX
Inateck 5 port PCIe USB 3 card
Pass though to OSX no issues, no driver or kernel issues, no special process just click the option in the VM settings tab and boom it works!
Sabrent USB sound card x2
I have one on each VM, again easy pass though and no driver/kernel issues
I have this set up as a 40TB server doing many things, along with running 2 VM desktops with GPU passthough. Each VM is 4 core 8 thread, 16gb ram and 1TB hdd. One is running Win 10 with dual users and other is OSX dual user. They are used as normal desktop stuff, slight gaming and have had no issues thus far, my OSX desktop has full control of the 5 port USB card, this way I do not need to pass anything though. I simply plug what USB items I want to use in the OSX VM and it shows up. Everything listed above works natively and did not require anything special to be done to make it work.
***Update***
Now have twin Strix GTX 970s and twin 5 ports cards installed.
3 VMs One controls RGB crap, one for desktop and one for HTPC running over IP hdmi extender with usb to other room