First Solo Build

As long as that HDD is free of bad sectors it'll be fine to use. Do note, however, Windows licensing is based on motherboards. So when you change the mobo, it will make you reactivate your copy of windows. You should do a full reinstall anyway, for driver issue purposes.

Your PSU looks good. No need to buy the new one.

Original build

1. Cant recommend the water cooling solution ...overpriced, underperforming and loud.

2. Is budget an issue ? that's a lot of MoBo unless you have specific features you want, lower cost solutions would serve just as well

3. 3 TB and larger HDs have a substantially larger failure rate then 2 TB drives. Also, be aware that while your SSD will boot ya PC a bit faster, it doesn't do squat for all the stuff on the HD. Recommend a SSHD here

4. What resolution monitor ?

5. The 5 meter LED strip is way way too long, stick to the 1 or 2M Phanteks branded options

6. The 1080 is kinda dead at this point, squeezed in between the Ti and the 1070.... depending on resolution, I'd move up or down a step.

As to the changes ...

1. the 7600k is a great option when budget limits choices and you have no need for video editing, CAD and things like that.

2. The Thermaltake is a cheap imitation of a "real" water cooling solution with it's cheap aluminum radiator and teeny pump. it just doesn't stand up to other components in its price range. Look at 23:00 mark of video.

https://www.youtube.com/watch?v=PYKdKVxbnp8

The Thermaltake w/ 2 x 120mm fans manages just 68C at 54 dbA while the Swiftech manages 65C at 43dbA.. That makes the Thermaltake more than twice as loud to provide 3C less cooling. On top of that, the Swiftech gives you a reservoir, a copper radiator, no mixed metals, a 1 gpm pump and the ability to add a water block on your GFX card since the system isn't closed and can be expanded.

http://www.swiftech.com/h320x2.aspx

And that's the 2 x 120mm Swiftch model... add 50% MORE cooling with the 3 x 120mm model ... all that for just $4 more.

http://www.swiftech.org/images/products/H320-X2-COLOR-PICS.jpg

Read this link to see what happens over time with aluminum rads and copper blocks

https://martinsliquidlab.wordpress.com/2012/01/24/corrosion-explored/

4. MoBo... check out the lower cost $40 lower) of the other K7 model, the link below compares features and i don't see anything worth the $40 other than the rebranded audio sunsystem

https://www.newegg.com/Product/Productcompare.aspx?CompareItemList=%2D1%7C13%2D128%2D963%5E13%2D128%2D963%2C13%2D128%2D964%5E13%2D128%2D964

If you are looking for more features and aesthetics, specifically with regard to overclocking, may want to look at the MSI XPower MoBo/// its $100 more but it looks great in the Phanteks Evolv TG Silver case
https://www.newegg.com/Product/Product.aspx?Item=N82E16813130968

I have a build waiting for the AIB 1080 Tis to drop and user wants Silver RAM
https://pcpartpicker.com/product/gVcMnQ/gskill-memory-f43000c15d16gvs

5. Still a great case.

6. May want to select RAM color to match MoBo highlights if aesthetics matter.

The CXM series is not something I 'd put in a new build but it is more than serviceable.
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story6&reid=486

The HD certainly can be used ... but how old is it ? I retire them to backup service after 3.5 to 4 years

I would make some changes.

I assume from the GTX1080, that this will be used primarily for gaming.

1. On the cpu, a I5-7600K is very good so long as you will overclock it. That is easy to do, but if you will not, then it is better to spend $100 more and run a I7-7700K at stock.
In either case, there is no need for liquid cooling.
A noctua NH-U12s or NH-U14s will cost less, be easier to mount, and cool sufficiently well.
See my rant on liquid cooling at the end.

2. A GTX1080 will want about a 520w psu. While the CX corsair units are prone to failure, they are not dangerous so I would continue to use it.

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.

Canned response to canned rant

As has been noted before, the canned rant only applies to CLC type liquid cooling ... certainly not custom loops or AIOs with copper rads which:

-certainly do cool better as evidenced by test results in above video and can cool quieter than air coolers.
-radiators are properly oriented only one way (intake) and actually lower inside case air temp due to the extra fans producing a higher turnover rate... 3 fans pushing air in means 3 fans worth of hot air being pushed out of the case. Air coolers remove 0 hot air from the case. Neither option has a measurable impact on the performance of inside the case components.
-Air exits the rads at 2-3C hotter than it comes in. Assuming for a moment that it wasn't being forced out within a half second and replaced immediately be cool air coming in, what component is it that is going to be affected by 28C as opposed to 25C ? CLCs operate at higher Delta T so is a lil bit hotter.
-That case comes w/ 3 fans ... adding the additional intakes makes it 6 fans and thereby lowering inside case temps significantly (verified on test bed). Case interior air volume is about 1.78 cuft. Even at 50% of rated fan air flow that's the entire case volume being turned over bringing in fresh outside cool air about every 0.53 seconds or 115 times a minute
-Adding 3 140mm case fans exhausting air on top ? bad idea.... that makes 2 fans blowing in with air inlet filters restricting air flow and 4 fans blowing out w/ no restriction.... end result about 3 x the flow going out as in leading to strong negative case pressure. So the air preheated by the CPU (90-120 watts) will exit the top, and hot exhaust air from the 250 watt GPU and the 650 watt PSU will be sucked back into the case thru the rear case grilles. With the top fans as intakes, positive pressure... no hot exhaust will be sucked back in and no dust along with it. Don't see any value in pushing a smaller amount of heat out, only to suck a larger volume of heat back in.

From a cooling perspective ... custom loops > OLC AIOs > best air coolers > CLCs
From a noise perspective ... custom loops > best air coolers > OLC AIOs > CLCs

I agree.... no reason to toss a serviceable PSU away, and it's more than enough if not overclocking.

PCPartPicker part list: https://pcpartpicker.com/list/FDPKbj
Price breakdown by merchant: https://pcpartpicker.com/list/FDPKbj/by_merchant/

CPU: Intel Core i5-7600K 3.8GHz Quad-Core Processor ($234.89 @ SuperBiiz)
CPU Cooler: Noctua NH-D14 65.0 CFM CPU Cooler ($65.95 @ Amazon)
Motherboard: Asus TUF Z270 MARK 2 ATX LGA1151 Motherboard ($138.99 @ SuperBiiz)
Memory: G.Skill Ripjaws V Series 16GB (2 x 8GB) DDR4-2400 Memory ($101.99 @ Newegg)
Storage: Samsung 850 EVO 250GB M.2-2280 Solid State Drive ($97.89 @ OutletPC)
Video Card: Gigabyte GeForce GTX 1080 8GB G1 Gaming Video Card ($529.98 @ Amazon)
Case: Phanteks Enthoo Evolv ATX Glass ATX Mid Tower Case ($189.99 @ Amazon)
Total: $1359.68
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-03-28 10:22 EDT-0400

As long as you overclock this you should be fine

For me I just used MSI OC Genie. It did everything for me. It won't bottleneck but overclocking is always a good idea. If you don't trust yourself then don't do yourself. You could always do research and look on YouTube for your specific motherboard

^^ Good to know. I was always told that ASUS was a very good brand for motherboards