Need: Guidance to pick components for gaming build

There are a number of PSU Wattage calculators on the web. Just plug in everything you're including in the build and they will give you the Wattage rating needed. Don't forget miscellaneous stuff like keyboard and mouse and whatever else you may attach that takes its power from the system.

When doing the calculation you might also include any future upgrades you are thinking of so you won't have to buy a new PSU when you upgrade.

Do not go cheap on the PSU. Everything else depends on clean, stable power so get a quality built PSU. This is not an item to cut corners on.

In the UK, swap the case with a Thermaltake Suppressor. They're criminally cheap there. I'm running a F51 myself and they are really really silent.

CPU cooler: I'd probably go with an air cooler. Most liquid coolers aren't really less noisy than a good aircooler, on the contrary. The fact that the rad will be mounted at the outside of the case can increase the noise heard with a sound dampened case.
I'd look at Be Quiet!'s dark rock/dark rock Pro series. You'd need low profile ram with those, like Corsair Vengeance though.

As for case fans: silent as possible go for BeQuiet Silent Wings. Not the best cooling performance but usually completely sufficient and inaudible
Noctua make really good fans as well.

As for the PSU, the Corsair RMx/RMi series is what you're looking for basically. Maybe Seasonic's new prime lineup.

As for the​ GPU, the 1070 is good. But for silent operations, don't go with the founder's edition linked but with a model with 2 or 3 fans.
Don't get the KFA² Galax either although a good card, it's not semi-passive cooled.
Asus, MSI, Gainward, Palit, Inno3d would be my choices, EVGA, Zotac & Gigabyte tend to be a bit louder, although the difference is very little and you probably won't notice.

Do not overthink the wattage you need.
500w is fine for a GTX1070, and 600w will run even a GTX1080ti:
http://www.realhardtechx.com/index_archivos/Page362.htm

Buy only quality, tier 1 or 2 from a list like this:
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html

Seasonic is always good.
You will not save anything in electricity with gold rating, but the fan is likely to run less, or not at all.
You can accomplish the same thing by overprovisioning a bit, say 20% so that the psu loafs.
Since you will be using most of the leads anyway, I do not see much value in modular. Not a negative though.

With a i5-7600K you should plan on overclocking.
How high you can go will be determined by the quality of your chip.
As of 1/13/17
What percent of samples can get an overclock
at a vcore around 1.4v.
I5-7600K
5.1 28%
5.0 52%
4.9 72%
You will run out of safe vcore before you run into thermal limits.
In a well ventilated case like yours, there is no need for liquid cooling.
I would use one of the new noctua s variant coolers.
I use a NH-U12s with my I5-7600@4.8.
You should use the NH-U14s or even the NH-D15s.
The s variants are designed to clear ram and graphics card backplates in the first pcie x16 slot.
See my canned liquid cooler rant at the end.

Intel is not sensitive to ram speed. 3200 is fine.
Here is a study:
http://www.silentpcreview.com/article1478-page1.html

Kaby lake is dual channel.
No advantage with 4 sticks which will cost more for the same capacity.
Really, unless you have a specific ram intensive app, 16gb isfine. Buy a 2 x 8gb kit. If you really want 32gb, buy a 2 x 16gb kit.

Your case comes with two front 140mm intakes which is optimal.
All air will be filtered so your case will stay cleaner.
Use no more than the single rear 120mm fan for exhaust. More/stronger will draw in unfiltered air from adjacent openings.


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.

Games depend mostly on the performance of the single master thread.
The I5-7600K runs at 3.8 stock with a turbo of 4.2. That is fine for any game.
But... Intel sells the K suffix processors with the intention that they can be overclocked.
Overclocking is somewhat of a misnomer.
In the bios, you simply raise the multiplier from the stock 38 a little at a time to a higher number.
Then test with some sort of a stress tester like OCCT.
The result is perhaps 25% better performance.
You need not do it initially, but you will have the wherewithal if you want to experiment.

IMHO The I5-7600K is the best gaming cpu available today.
Perfectly good for any graphics card you want to use.

not sure which fans come with the 450D
if they are the new ML fans, they're alright
if they are the old SP/AF-fans you might wanna consider changing them if the cash is no concern for you. best bet is to try it and if you think it's loud or too light then change them.
board is nice, RAM speed doesn't matter too much. I don't know if things have changed but 3200MHz RAM _can_ or _could_ be a pain to get to work; 3000 MHz is the sweet spot these days -- the difference is very minor though. honestly even 2133MHz RAM will probably get you about the same performance.