My nephew asked me to help out in building his first gaming machine and thought I'd ask everyone here who's more up to date with the latest components than I am. This list is something he has come up with and would like to know what you folks think of it and/or any suggestions to improve it.
   
Edit: Updated List: https://pcpartpicker.com/list/g9k4LD
Thanks,
Mesh

The only thing that might concern me is the power supply. That big video card + the 7700k will be sucking quite a lot of watts under a full load. Though the 550 watt supply may handle it fine now, it may not be adequate after adding/upgrading in the future. I would be much more comfortable bumping the watts up to 650. Just my opinion based on past experience. The less a power supply has to work to keep up, the better.

Thanks Darin, good point on the PSU. I'm a little concerned on the CPU cooler as well.....would that Phanteks be enough for his gaming? (he may or may not do a little OCing....he's going to decide on that out later). Any recommendations would be greatly appreciated (I know my NH-D14 is excellent, but it's also huge and his case may not be big enough). 
Also, not sure how good those SSD and HD drives are... 

I agree on the Power supply, may even go up to an 800 watt (and good quality, not a cheap model).  I wouldn't think a $49.99 case would make a good gaming PC case.  Probably does not have the fans or capability for potential multiple fans or even the space for some video cards.  I also like liquid CPU coolers.  I've used them in the past and have one in my current (6 month old) build.  I first tried a Noctua CPU cooler, as Noctua had a good reputation and is quiet.  It was quiet and barely fit in my case but ran relatively warm at idle (approx. 40 degrees C).  I replaced it with a Deepcool Captain 120EX and it dropped the idle temps down to around 30 degrees C, a much better temp (load does not rise like the Noctua either). The Captain 120EX is quiet, too.  I've had Corsair liquid coolers in the past and the fans are noisy in them (a common complaint).  The ASUS motherboard I have is sold as a "gaming" motherboard. 

Thanks Jack....I'm putting together a new parts list from the recommendations by all of you. Stability/decent quality being the most important factor, and of course the cosmetic look.....current color scheme being white (teenagers ). Will read some reviews on MB's and I'm thinking something under $200 might do him well?
 
I forgot to mention, his budget is around $2000 and he's thinking of doing some video editing/graphics design etc... as he's looking into a degree for college. Hopefully, this machine will help in all that.  

The Deepcool Captain 140X  which may be better than the 120EX for his applications, comes in White and with lights in the CPU heatsink/pump.  That would work with the white case if it had a window on one side of the case, as many do.  The ASUS ROG motherboards also have colored lights, that the "young" gamers like to have.
 
 

Thanks again Jack!!
So far, this is what I've come up with (haven't discussed this with my nephew yet). Any thoughts on the ASRock Fatality Gaming Z270 KC motherboard?
 
https://pcpartpicker.com/list/PmPCRG

I've had two ASRock Fatal1ty motherboards.  A Z77 and a Z170, both had hardware problems initially and were returned for other brands.  Maybe I just had bad luck.  

Mesh
Thanks Darin, good point on the PSU. I'm a little concerned on the CPU cooler as well.....would that Phanteks be enough for his gaming? (he may or may not do a little OCing....he's going to decide on that out later). Any recommendations would be greatly appreciated (I know my NH-D14 is excellent, but it's also huge and his case may not be big enough). 
Also, not sure how good those SSD and HD drives are... 

Hard drives seem to be really hit and miss lately according to reviews I've read. Especially the less expensive ones. I have several Western Digital Black series hard drives that have been great the last couple of years (3x 3TB and a couple 1 TB models). I use one of these for my samples in my music PC. The others are used for video editing workstations (my real job). However, I've noticed people having some issues with the newer 4TB and up models. Mainly 'clicking' noises and such. Western Digital has just released the 'Gold' series, which are touted to be faster than the Black series, and very reliable. I just ordered a 1TB model to try out. The Black series and Gold series are both on the higher-end, expensive drives though. Of the lower-end drives, I've had good luck with Western Digital also, but they seem to be having some QC issues of late. Just be sure you get at least a 7200 RPM drive. I would read reviews on NewEgg before deciding on one.
 
As for SSD drive.. Samsung is considered king. I've not tried any other brand, but others may be just fine. Again, best bet is to read reviews.
 
Just some food for thought: I just built this system (literally last weekend) for my new video editing system:
 
Processor:
Intel Core i7-7700K Kaby Lake Quad-Core 4.2 GHz LGA 1151 91W BX80677I77700K Desktop Processor
 
Motherboard:
GIGABYTE GA-Z270-Gaming K3
 
Memory:
CORSAIR Dominator Platinum 32GB (4 x 8GB) 288-Pin DDR4 SDRAM DDR4 3000 (PC4 24000) Desktop Memory Model CMD32GX4M4C3000C15
 
System Drive:
SAMSUNG 850 EVO 2.5" 500GB SATA III 3-D Vertical Internal Solid State Drive (SSD) MZ-75E500B/AM
 
Case:
Phanteks Enthoo Luxe PH-ES614LTG_BK Black Aluminum Faceplates Tempered Glass Panel Steel Chassis ATX Full Tower Computer Case with RGB Illumination
 
Power:
Seasonic Flagship PRIME SERIES SSR-1000GD 1000W GOLD FULL MODULAR ATX12V & EPS12V 135mm FDB Fan Super Quiet Power Supply
 
Video:
EVGA GeForce GTX 1060 SC GAMING, ACX 2.0 (Single Fan), 06G-P4-6163-KR, 6GB GDDR5, DX12 OSD Support (PXOC), Only 6.8 Inches
 
Windows 10 Pro
 
I also added in some other stuff of little relevance to anyone but myself. I spent about $2000 total.
 
The system was a breeze to set up, and very fast.. Did I say FAST? Lol. The trouble I ran into was with the heat-sink/fan that I purchased. The 7700k runs pretty hot. The stock K-Series Intel heat-sink/fan I ordered just doesn't cut it. The CPU was getting close to 100 degrees celsius under load. FAR too hot. So I've ordered a Noctua NH-D15 to hopefully solve the problem. The full-tower case I have should accommodate it.
 
Other than the above problem, this system has been very stable in the little time that I've had it. Adobe Premiere, After Effects and Photoshop are a pleasure to work.
 
Your nephew will probably want the bigger video card that you have already picked out. That thing looks like a beast! I've had great luck with both Gigabyte and EVGA video cards.
 
As for the memory, he doesn't really need the 32GB that I used. There is a 16GB kit of that RAM available that would probably be plenty enough for a gaming rig. If he does decide to start doing video editing and graphics etc., he would very much appreciate the 32GB.
 
I purchased all of these parts from NewEgg.com.
 
Edit:
I forgot to mention that the 1000 watt power supply is complete overkill, even for me. Lol. Also, if he wants to stick with a mid tower case, Jack's suggestion on a water cooling solution is certainly something to consider.
 

Thanks again Darin for the detailed/excellent post.....it was very helpful.
 
I was looking at the graphic cards and that crypto currency thing has just made it ridiculously expensive for any mid range cards. It seems you'll have to buy below that or higher end cards to "get your moneys worth" .
 
The Gigabyte GeForce GTX 1080 Ti Aorus Xtreme Edition seems to be a hit by most reviewers (very expensive as well)......that should be more than enough for anything he needs to do (gaming/video editing etc...adding more RAM of course).
 
I'm currently looking into MB's under $200 and the ASUS Prime Z270-A seems to be a good fit for this build......but, will keep looking.