Buying a new pc

First of all, what is the purpose of this new PC? Gaming?

If you don't ever intend to OC Go.for the non-k 7700 and a decent H270 board and a cheap yet decent air cooler like a Cryorig M9i

Usually the RMx is within 15$ to other units of the same quality. A 650W unit that costs less than 70$ is somewhat dodgy and I wouldn't spend a dime on it. Look at Super Flower;, EVGA G3, GS, B2, G2; XFX (except the XT) or Seasonic. Pick the one that looks best to you. But I wouldn't go for less than that.
Cheaper units come with less safety, stability, some outright lie about their specs (especially those who claim 650W for 35$(

To cut back on price you can go with an i5-7600
For gaming there's little difference.

there is n point in getting a "k" processor if you don't plan to OC.. BUT there is no point in getting such expensive components and not OCing.. this set up is ideal for OCing.. it would be a shame not to take advantage of the offering of your budget.. The "Z" M/B offers OC to "K" CPUs and some other features that only a few are truly needed..
My only recommendations are about the ram and the disk
RAM does not need to have such high freqency but if it fits our budget w/o need to save up from smth more critical (don't really know how you end up on these so they might be good for you)
SSDs are not designed to keep data, but for programms.. the thing is that in my opinion a 250GB SSD is enough for OS and some critical programms(such as your browser etc) and a HDD for other stuff. it won't affect gaming performance.. only loading times..
PSU is very good in value and fidelity. Also it is modular and 80+ Gold , features that get the cost high

You could build as is, it is an excellent pc.
To save a bit, here are some thoughts:

1. On ram, there is very little difference due to ram speed. 2400 is fine.
http://www.silentpcreview.com/article1478-page1.html

Love the ssd.

2. On the motherboard, yes, you could use a cheaper B250 chipset if you will forgo the option of overclocking.
Look at M-ATX sizes, they are often cheaper.
The i7-7700K runs at stock 4.2 very well.
If you were to overclock, now, or in the future, this is what you might expect:
As of 1/13/17
What percent can get an overclock at a somewhat sane 1.4v Vcore.

I7-7700K
4.9 74%
5.0 56%
5.1 26%
5.2 5%

3. I do not recommend liquid cooling see my canned rant at the end.
In particular, a good $35 air cooler will be all you need.
Look at the scythe kotetsu, here is a review:
http://www.silentpcreview.com/Scythe_Kotetsu

4. GTX1080 needs about 520w.
I have no problem overprovisioning a PSU a bit. Say 20%.
It will run cooler, quieter, and more efficiently in the middle third of it's range.
A PSU will only use the wattage demanded of it, regardless of it's max capability.
Do not skimp on psu quality.
Buy a tier 1 or 2 unit from a list such as this:
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html
You can't go wrong with Seasonic. To save a bit, ignore gold rating and modular.
I might suggest a Seasonic s12II 620w at half the price:
https://www.newegg.com/Product/Product.aspx?Item=N82E16817151096

5. Cases are a personal thing.
If you buy a M-ATX sized motherboard, I can personally recommend the Silverstone TJ-08e case.
It is compact, and has a washable front intake air filter.
https://www.newegg.com/Product/Product.aspx?Item=N82E16811163182

My canned rant on liquid cooling:
------------------------start of rant-------------------
You buy a liquid cooler to be able to extract an extra multiplier or two out of your OC.
How much do you really need?
I do not much like all in one liquid coolers when a good air cooler like a Noctua or phanteks can do the job just as well.
A liquid cooler will be expensive, noisy, less reliable, and will not cool any better
in a well ventilated case.
Liquid cooling is really air cooling, it just puts the heat exchange in a different place.
The orientation of the radiator will cause a problem.
If you orient it to take in cool air from the outside, you will cool the cpu better, but the hot air then circulates inside the case heating up the graphics card and motherboard.
If you orient it to exhaust(which I think is better) , then your cpu cooling will be less effective because it uses pre heated case air.
And... I have read too many tales of woe when a liquid cooler leaks.
google "H100 leak"
I would support an AIO cooler only in a space restricted case.
-----------------------end of rant--------------------------

Your pc will be quieter, more reliable, and will be cooled equally well with a decent air cooler.

I disagree with the non-K comments, the K has a base clock speed of 4.2 boosting to 4.5, the non K has 3.6 boosting to 4.2.

For the tiny extra cost the k is much better value.

Ditch the Z board by all means.

^agree