So... if it were me:
CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($234.39 @ Amazon)
CPU Cooler: Swiftech H240-X 90.0 CFM Liquid CPU Cooler
Thermal Compound: Arctic Silver 5 High-Density Polysynthetic Silver 3.5g Thermal Paste ($5.88 @ OutletPC)
Motherboard: Asus MAXIMUS VIII GENE Micro ATX LGA1151 Motherboard ($206.99 @ SuperBiiz)
Memory: Kingston Savage 16GB (2 x 8GB) DDR4-3000 Memory ($114.99 @ SuperBiiz)
Storage: Samsung 950 PRO 256GB M.2-2280 Solid State Drive ($186.99 @ SuperBiiz)
Storage: Hitachi Ultrastar 7K3000 3TB 3.5" 7200RPM Internal Hard Drive
Video Card: Sapphire Radeon RX 480 8GB Video Card ($269.99 @ B&H)
Power Supply: EVGA SuperNOVA T2 750W 80+ Titanium Certified Fully-Modular ATX Power Supply ($167.04 @ Newegg)
Case Fan: Noctua NF-A14 industrialPPC-2000 PWM 107.4 CFM 140mm Fan ($35.36 @ Amazon)
Monitor: Asus MG278Q 27.0" 144Hz Monitor ($511.13 @ B&H)
^^^--- push it to $2000 with one of these:
(or hell, save on a cheaper case and up your hardware elsewhere)
Why this build???
titanium psu: stable overclock
high rated cooling: overclock (throw that noctua in the spot behind the mobo on the lian li case)
Monitor: 144hz, 1ms response FREE SYNC, 2k (honestly 2k is plenty of res for me, 4k is overkill)
gpu: realistically I feel like the 480 can handle just about anything at 2k with ample smoothness when coupled with yonder freesync monitor.
Please critique my build! If I'm messing up i wanna know, cause I plan on doing this one for myself soon.
EDIT: I did not see the "this one is a must have, he likes this one" next to the gtx1080. Sorry for wasting your time folks, my build falls apart when spending that much on the graphics card.