Building ITX System, please help

[xSYNx]

Hey All ~  Looking for a little advise on a build I'm trying to get done in the next few months.  Essentially, I'm moving into a Tiny House with my wife and we are short on space.  I hate gaming on a Laptop and my current system, while it runs great now, is just flat out WAY TOO BIG for what I'm currently running.

 

Here is what I would like to keep and use in the new system... everything is open to negotiations

 

Keeping my EVGA 970 GTX with NZXT Kraken x41 closed loop water cooler.

2 SSD's and a couple of USB 3.0 Drives

and an ATX 850 Watt powersupply

 

Here is what I'm looking at getting.  Would like input as I've never built an ITX system before

 

Case: Fractal Design Define Nano S

CPU: Intel Core i5-6600K 6M Skylake Quad-Core 3.5 GHz LGA 1151 91W BX80662I56600K Desktop Processor Intel HD Graphics 530

Cooling:  NZXT Kraken X41

Mobo: ?????

Memory: ?????

 

This is going to be a Gaming PC, and I am doing the water cooling for two reasons, it's quieter, and keeps things cooler if I decide to OC in the future.  

 

I know the Fractal Design case will support the 140 mm fans and radiators.  But which MOBO and MEMORY will best suit this system?  I may upgrade the GPU in the future too.  

 

Thanks in advance.

[GDRRiley]

http://pcpartpicker.com/product/TykwrH/asus-motherboard-z170iprogaming for a mobo grab that memory doesn't really mater just grab some DDR4 about 16gb should do well