Get an i5 7600, unless you plan/are a content creator. The PSU is a bit much you could get a 650W and be just fine. Wait for a 1080 Ti, its expected to be roughly the same price I believe. You don't really need a water-cooler unless you're going to be an overclocker, air-cooling is fine. Honestly, you could get a 500 GB SSD and still get a 1TB HDD and still save money (the jump from 1TB to 500 GB on the SSD is 200$ on newegg.) I would find a different motherboard, either by just downgrading to something cheaper while keeping the chipset (z270) or just go with a z170 board. Especially since you'll only have one thing in your PCI slots. I'd find a different case though. Seems a bit costly considering it just holds everything inside.
I only play CS:GO so I can't really talk about other games, but CS needs a powwahhhfull CPU. Also, when u spend that kind of money, you might as well get a proper CPU unless you want to upgrade next year. I'll get Ryzen next month...
But... does that really make your opinion that valid though? Your advocating him on getting the most expensive consumer CPU available because you think all games need it for the high resolution, a job that is mostly, if not entirely, focused onto the GPU. And even if it was you'd get barely noticeable frame improvements. The CPU is more important for things that involve AI like Cities Skylines. Its not even like CS is that good looking a game compared to like Battlefront/Field Crysis or Destiny. Yea I view it as overhyped even though it is always top 10 most watched game during the day but then again I've never been the biggest fan of PvP so...
MMOs are so nice... not nearly as many people rage at you for having a bad time.
I do not understand why you recommend the most powerful single GPU on the market and then tell them to get a shitty CPU. I know, most games can be played with that lower end trash i5 but most games can also be played with an i3. If you are going to drop 4k (money) on a PC you might as well get something to last you a long time.
I find it difficult to explain why I think I am right but most of the times I am right.
Personally I'd say to get a 1070 or to get a regular 1080 when the Ti comes out (because that price would most likely drop). Not like he's using a 4K monitor. But everyone seems to want to make it a Ti. 4K is very demanding for a card, At least he wants a 1440p which is very less demanding. Its still demanding (which warrants at least a 70 imo). But why not just get a last gen CPU or two gens old like I have (a 4790k, too much for me).