Good build for 1440p gaming?

Do you only game? If not streaming, 8600k and a cheaper cooler is enough. ram too small, 16 gb is standard nowadays. PSU is no good. 24 inch too small for 2k. My edits:

PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor ($239.00 @ SuperBiiz)
CPU Cooler: CRYORIG - H5 Universal 65.0 CFM CPU Cooler ($46.89 @ OutletPC)
Motherboard: ASRock - Z370 Extreme4 ATX LGA1151 Motherboard ($153.89 @ OutletPC)
Memory: G.Skill - Ripjaws 4 Series 16GB (2 x 8GB) DDR4-3000 Memory ($159.99 @ Newegg)
Storage: Crucial - MX500 500GB 2.5" Solid State Drive ($109.95 @ Adorama)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($42.89 @ OutletPC)
Video Card: EVGA - GeForce GTX 1080 8GB Superclocked Gaming ACX 3.0 Video Card ($549.99 @ B&H)
Case: NZXT - S340 (White) ATX Mid Tower Case ($59.99 @ Newegg)
Power Supply: EVGA - SuperNOVA G3 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($79.89 @ OutletPC)
Monitor: Dell - S2716DG 27.0" 2560x1440 144Hz Monitor ($435.00 @ Amazon)
Speakers: Logitech - Z200 0W 2ch Speakers ($21.75 @ Newegg)
Total: $1899.23
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-06-07 14:51 EDT-0400
 
just poor quality, evga makes both good and bad quality psus. Most important is cap no good.

If steaming ->

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 7 2700X 3.7GHz 8-Core Processor ($319.79 @ SuperBiiz)
Motherboard: MSI - X470 GAMING PLUS ATX AM4 Motherboard ($129.99 @ Amazon)
Memory: G.Skill - Trident Z 16GB (2 x 8GB) DDR4-3200 Memory ($174.99 @ Newegg Business)
Storage: Crucial - MX500 500GB 2.5" Solid State Drive ($109.95 @ Adorama)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($42.89 @ OutletPC)
Video Card: EVGA - GeForce GTX 1080 8GB Superclocked Gaming ACX 3.0 Video Card ($549.99 @ B&H)
Case: NZXT - S340 (White) ATX Mid Tower Case ($59.99 @ Newegg)
Power Supply: EVGA - SuperNOVA G3 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($79.89 @ OutletPC)
Monitor: Dell - S2716DG 27.0" 2560x1440 144Hz Monitor ($435.00 @ Amazon)
Speakers: Logitech - Z200 0W 2ch Speakers ($21.75 @ Newegg)
Total: $1924.23
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-06-07 15:16 EDT-0400

2700X vs 8700k streaming: https://www.gamersnexus.net/hwreviews/3287-amd-r7-2700-and-2700x-review-game-streaming-cpu-benchmarks-memory/page-2