I've been wanting a new gaming rig but I also want to upgrade my urnaid/plex server so maybe I can bang them both out in one? 

 

I've been watching the nice Xeon E5-2670 setups and that seems great for plex, transcoding, etc with room to run some vms for testing. If I go with the ASRock motherboard will this handle a nice graphics card and will playing games affect other stuff with this type of setup? I'm assuming I could allocate 4 cores to the gaming rig and the rest to unraid which with a 1070 GTX or something would allow me to play pretty much any game? Any issues with this kind of setup?

That is pretty much the exact setup that I have. I have a different motherboard (Intel S2600CP2J)

 

I pass through a Renasas chipset USB 3.0 PCIe card for my Windows 10 Gaming VM.

 

I use IsolCpus to isolate all of the second CPU from unRaid and then allocate the first of each of the 8 hyperthreaded pairs to the Windows 10 VM (cpuset 8 - 15). Make sure that the GPU is installed in a slot that is allocated to the CPU that you are using for the Gaming VM.

 

I had to use OVMF and i440FX2.5 for the Win10 VM and then passthrough of the GTX1070 was a breeze.

 

I get good smooth gameplay on Games Like Rise of the Tomb Raider. Rendered at 1440P and then downsized to 1080P (+60 FPS).

 

I used Noctua CPU coolers and case fans and the rig as a whole is cool and quiet.