Is this a good Pc

Solution
You don't need a 850w psu. A good 650w is plenty more than you need. Take the extra $20 and put it towards a decent 250Gb ssd that'll get used as primary boot/OS drive and for the odd important stuff like main Steam directory. The actual game files you keep on the hdd as they'll see little use after initial load as everything will be run through the ssd as cache drive. It's best of both worlds, ssd speeds with hdd capacity without the massive price tag of a 1Tb+ ssd.
I made some revisions.
PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor ($238.99 @ Amazon)
CPU Cooler: Scythe - FUMA Rev.B 79.0 CFM CPU Cooler ($46.99 @ Amazon)...
Does an $150 more SSD with half of the storage make a big difference. I just don’t see why it is so much more expensive with 1TB less At least the one I was looking at
 
Everything will load way faster... Once you go SSD you'll never go back. If you need more space for other stuff than get a standard HD. I;ll never buy another SATA HD again. Only SSD Drives.
 
You don't need a 850w psu. A good 650w is plenty more than you need. Take the extra $20 and put it towards a decent 250Gb ssd that'll get used as primary boot/OS drive and for the odd important stuff like main Steam directory. The actual game files you keep on the hdd as they'll see little use after initial load as everything will be run through the ssd as cache drive. It's best of both worlds, ssd speeds with hdd capacity without the massive price tag of a 1Tb+ ssd.
I made some revisions.
PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor ($238.99 @ Amazon)
CPU Cooler: Scythe - FUMA Rev.B 79.0 CFM CPU Cooler ($46.99 @ Amazon)
Motherboard: Gigabyte - Z370 AORUS GAMING WIFI (rev. 1.0) ATX LGA1151 Motherboard ($183.88 @ OutletPC)
Memory: Corsair - Vengeance LPX 16GB (2 x 8GB) DDR4-3000 Memory ($159.99 @ Best Buy)
Storage: Crucial - MX500 500GB 2.5" Solid State Drive ($103.99 @ SuperBiiz)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($58.89 @ OutletPC)
Video Card: EVGA - GeForce GTX 1070 8GB SC GAMING ACX 3.0 Black Edition Video Card ($399.99 @ Amazon)
Case: NZXT - S340 (Black/Red) ATX Mid Tower Case ($49.99 @ SuperBiiz)
Power Supply: EVGA - SuperNOVA G3 650W 80+ Gold Certified Fully-Modular ATX Power Supply ($69.99 @ Amazon)
Case Fan: Phanteks - PH-F120SP_RLED 54.4 CFM 120mm Fan ($11.99 @ Newegg)
Case Fan: Phanteks - PH-F120SP_RLED 54.4 CFM 120mm Fan ($11.99 @ Newegg)
Speakers: Insignia - NS-PCS20 0W 2ch Speakers ($14.99 @ Best Buy)
UPS: CyberPower - AVRG750U UPS ($79.95 @ Amazon)
Total: $1431.62
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-07-15 23:04 EDT-0400

Also, that UPS won't work as intended. New psus with Active pfc don't work on simulated sinewave. You'll need a pure sinewave model/smart model for that.

 
Solution
Karadjdne make a good point... But I game on Steam, and it loads faster straight up. Night and day from my standard HD. SSD has come done in price now. You can get a 1TB SSD for under $200 if your on a budget. Now your only $120 difference from that HD. It will be the best money you spend on that build. It will complement the speed of the CPU nicely.
 
I game in steam too, with main steam files on ssd, game files on hdd. Once the game initially loads, it'll use the ssd as cache drive, everything is ssd speeds the only time the hdd is used is when the game is closed and any changes are made to original files. Even the saved games are under the main steam files, so in game changes are on the ssd. Works that way for anything run through or activated by the OS, which is basically everything.
 
You missed the point. That video shows gta5 loaded through ssd and loaded through hdd. What it doesn't say is that that game is on a hdd only pc. After initial load, there's exactly no difference between a game that's on hdd run through ssd and a game on ssd run through ssd, because they are both run through ssd cache. They are identical. The only difference is original source, after that everything is SSD
 
PCPartPicker part list / Price breakdown by merchant

CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor ($238.99 @ Amazon)
CPU Cooler: CRYORIG - H5 Universal 65.0 CFM CPU Cooler ($46.99 @ Newegg Marketplace)
Motherboard: ASRock - Z370 Killer SLI/ac ATX LGA1151 Motherboard ($141.88 @ OutletPC)
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3000 Memory ($154.99 @ Newegg)
Storage: Kingston - A400 240GB 2.5" Solid State Drive ($53.83 @ Newegg Marketplace)
Storage: Seagate - Barracuda 2TB 3.5" 7200RPM Internal Hard Drive ($58.89 @ OutletPC)
Video Card: EVGA - GeForce GTX 1070 Ti 8GB SC GAMING ACX 3.0 Black Edition Video Card ($439.99 @ B&H)
Case: NZXT - S340 (Black/Red) ATX Mid Tower Case ($49.99 @ SuperBiiz)
Power Supply: SeaSonic - FOCUS Plus Gold 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($64.99 @ Newegg)
Case Fan: Cooler Master - SickleFlow (Red) 69.7 CFM 120mm Fan ($8.24 @ OutletPC)
Case Fan: Cooler Master - SickleFlow (Red) 69.7 CFM 120mm Fan ($8.24 @ OutletPC)
Speakers: Insignia - NS-PCS20 0W 2ch Speakers ($14.99 @ Best Buy)
UPS: CyberPower - AVRG750U UPS ($79.95 @ Amazon)
Total: $1361.96
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-07-15 23:31 EDT-0400
 
The thing with drives....you can add more later as budget allows.

Start with a 250GB SSD for the OS and applications, and a 1-2TB HDD for all that other stuff.
A year from now, add a 1TB SSD for some games, keeping the original 250GB as still the OS/application drive.

Much easier to start with a good base, rather than to try to switch around later.
 


My point is inital load times.
 
I’m going to respectfully disagree with you on this. Installing games on an SSD drastically reduces it's load times. SSDs also reduce hitching in games causing a pause when it can’t pull from the hard drive.

If you’re building a $1500 computer why wouldn’t you spend the extra $150 and get a superfast SSD? To me, personally it makes no sense on a “new build”. Speed is everything in a PC. He’s budgeting in a $500 graphics card. He and you can google the statistics on SSD vs HD’s.