New builder looking for help with my first gaming PC. Looking to spend $2k> but my budget is flexible.

###Build Help/Ready:

Have you read the sidebar and rules? (Please do)

Yes.

What is your intended use for this build? The more details the better.

Mostly online gaming, possibly with some twitch streaming, HD movies, and day trading mixed in.

If gaming, what kind of performance are you looking for? (Screen resolution, framerate, game settings)

I want to be able to play games like PUBattlegrounds, Battlefield, and games coming out in the near future at max settings with 50+ frames at 1440p and games like CSGO with max settings at 144+ fps.

What is your budget (ballpark is okay)?

Preferably under $2000 including the OS and monitor. But I can be convinced to spend a little more.

In what country are you purchasing your parts?

US and A!!

Post a draft of your potential build here (specific parts please). Consider formatting your parts list. Don't ask to be spoonfed a build (read the rules!).

PCPartPicker part list / Price breakdown by merchant

Type	Item	Price
CPU	Intel Core i7-7700K 4.2GHz Quad-Core Processor	$337.88 @ OutletPC
CPU Cooler	Corsair H100i v2 70.7 CFM Liquid CPU Cooler	$109.99 @ Amazon
Motherboard	MSI Z270-A PRO ATX LGA1151 Motherboard	$111.98 @ NCIX US
Memory	*Kingston FURY 16GB (2 x 8GB) DDR4-2400 Memory	$82.98 @ PCM
Storage	Samsung 960 EVO 250GB M.2-2280 Solid State Drive	$127.98 @ NCIX US
Storage	Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive	$47.45 @ OutletPC
Video Card	MSI GeForce GTX 1080 8GB DUKE OC Video Card	$504.98 @ Newegg
Case	NZXT S340 Elite (Black) ATX Mid Tower Case	$89.99 @ SuperBiiz
Power Supply	*EVGA SuperNOVA G3 550W 80+ Gold Certified Fully-Modular ATX Power Supply	$69.99 @ Newegg
Operating System	Microsoft Windows 10 Home OEM 64-bit	$86.88 @ OutletPC
Monitor	Dell S2417DG 23.8" 2560x1440 165Hz Monitor	$469.00 @ Adorama
Prices include shipping, taxes, rebates, and discounts
Total (before mail-in rebates)	$2064.10
Mail-in rebates	-$25.00
Total	$2039.10
*Lowest price parts chosen from parametric criteria
Generated by PCPartPicker 2017-05-03 18:17 EDT-0400

Provide any additional details you wish below.

I'm not completely set on any of the specific components listed. If there is anything I can save money on while still getting the performance I want then I'll gladly edit the build with your suggestions. Another thing to note is this message from PC part picker: "The motherboard M.2 slot #0 shares bandwidth with a SATA 6.0 Gb/s port. When the M.2 slot is populated, one SATA 6Gb/s port is disabled". I'm pretty clueless when it comes to hardware so can anyone tell me if this will have an impact on my ability to use this build or upgrade it in the future? Or does the motherboard still have more than enough slots for me to use?

Appreciate any and all advice, thanks.