New Build Review

You are drastically overspending on the Cooler, RAM, and a bit on the motherboard.
I would choose cheaper options on those (Such as the H7 or H5, 16GB of any 2400 RAM thats not dominator, and a different board) and invest the money towards a better card, SSD, or processor.
 
You could do better for the budget.

PCPartPicker part list / Price breakdown by merchant

CPU: Intel Core i7-7700K 4.2GHz Quad-Core Processor ($338.89 @ OutletPC)
CPU Cooler: be quiet! Dark Rock 3 67.8 CFM Fluid Dynamic Bearing CPU Cooler ($59.88 @ OutletPC)
Motherboard: Gigabyte GA-Z270XP-SLI ATX LGA1151 Motherboard ($139.89 @ OutletPC)
Memory: G.Skill Aegis 16GB (2 x 8GB) DDR4-2800 Memory ($102.99 @ Newegg)
Storage: Crucial MX300 275GB M.2-2280 Solid State Drive ($89.88 @ OutletPC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($49.33 @ OutletPC)
Video Card: MSI GeForce GTX 1070 8GB Video Card ($399.99 @ Newegg)
Case: NZXT S340 Elite (Black/Red) ATX Mid Tower Case ($85.98 @ Newegg)
Power Supply: EVGA 850W 80+ Bronze Certified Semi-Modular ATX Power Supply ($75.99 @ Newegg)
Operating System: Microsoft Windows 10 Home OEM 64-bit ($88.58 @ OutletPC)
Total: $1431.40
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-02-18 14:59 EST-0500
 
Solution


that's a nice build, much better suited than the original.
would downsize the PSU to 550W
SLI is pretty much not worth it these days
 
@Isokolon, I agree a single more powerful card would be better (1080 or Ti depending on purchase date) but it also depends on the monitor the OP plans on getting as there are some decent improvements with 4K/60hz with dual cards. If just the i7 & GTX 1080 then the EVGA G2 650W would be more then enough for overclocking.

It does appear Nvidia/game developers are steadily moving away from SLI/CF drivers/support.