2019 Build

Intel - Core i7-8700K 3.7 GHz 6-Core Processor
The core looks like it's right for both price and performance. I don't know much about picking processors these days, but reviews for the 8700K make it seem promising. I'm inclined to stick with Intel because that's what I'm most familiar with and I'm generally the one doing IT work for the family.

Noctua - NH-U9S 46.44 CFM CPU Cooler
Despite not overclocking the processor, some sort of cooling system is probably required. Where we live tends to get humid, dusty, and hot with indoor temperatures sometimes hitting upper 80's to lower 90's during the summer. I've heard good things about the U9S, although I've never looked into large coolers prior to this build. While my greatest concern is that it might interfere with the RAM, Noctua's website claims the U9S is compatible with the motherboard I've selected.

Thermal Grizzly - Kryonaut 1g 1 g Thermal Paste
Good reviews, I'm inclined to trust Gamers Nexus regarding it, and it doesn't break the bank.

MSI - MPG Z390 GAMING PLUS ATX LGA1151 Motherboard
Picking a motherboard is another area I have next to no experience in. I've recently been turning to MSI as their products seem to be getting good reviews and my father hasn't run into any problems with the MSI laptop he's been using for about a year, so that's where I started. I looked for a number of features (ATX, compatible with the 8700K, USB 3.1, etc.) and the MPG Z390 Gaming Plus looked good and I didn't come across anyone complaining about it. Again though, I'm kind of guessing when it comes to selecting a good brand of motherboard and I'm not sure where to look up information regarding how much space is available for the cooler in relation to the RAM.

G.Skill - NT Series 16 GB (2 x 8 GB) DDR4-2133 Memory
G.Skill's warranty looked good, the sticks in question are DDR4, and 2133 is fine since my brother doesn't plan on overclocking. From what I've read online, higher than 2133 only makes a difference if you're overclocking.

Western Digital - Black NVMe 1 TB M.2-2280 Solid State Drive
Western Digital - Blue 1TB PC Hard Drive - 7200 RPM Class, SATA 6 Gb/s, 64 MB Cache, 3.5" - WD10EZEX
After having dealt with several different brands of HDD, I've settled on WD as the least likely to shart the bed unexpectedly. My brother intends to install most of his games on the SSD, hence the 1 TB of space and opting for NVMe.

MSI - GeForce RTX 2070 8 GB Video Card
I was going to pick a GTX 1080, but the RTX 2070 seems close enough in price to warrant the upgraded choice. We're sticking to Nvidia as a matter of personal preference.

Corsair - 750D Airflow Edition ATX Full Tower Case
The case is, ironically, the part I've agonized the most over. I want to optimize air cooling and this one looks like it has it in spades, but I'm concerned that I might be overdoing it a bit. We'll probably end up going for this one anyway, but if there's a case that can offer similar or better air cooling I'd like to know about it.

Corsair - RMx (2018) 650 W 80+ Gold Certified Fully-Modular ATX Power Supply
According to Outer Vision, this build will require 483 W, so a 650 W power supply should be good with a safe buffer of a little over 25%. A couple notes regarding the power calculations: 1) Outer Vision didn't have a Blu-Ray/DVD/CD Writer, so I just went with Blu-Ray. 2) The mother board comes with 23 red LEDs on it, so I went with "4 x LED strip light - 6 LEDs (4.7"/12cm)".

LG - WH14NS40 Blu-Ray/DVD/CD Writer
He wants to be able to watch both Blu-Rays and DVDs, as well as burn CDs.

Microsoft - Windows 10 Pro Full 32/64-bit
Personally, I prefer Windows 7 over Windows 10, but since he's wanting to be able to use this system for the next 5 years or so for gaming, Windows 10 it is. Pro edition so that he can have better control over when it updates.

(2x) Noctua - NF-A14 PWM chromax.black.swap 82.52 CFM 140mm Fan
The case comes with 3 fans, but I think 2 more would be prudent. I'm fairly certain that the three stock fans that come with the case are weaker than the two Noctua fans I've picked out, so my brother should have better control over the air pressure inside the case. He'll probably go for a negative pressure arrangement, but ultimately it'll depend on how fast dust builds up inside the case.

Asus - VG248QE 24.0" 1920x1080 144 Hz Monitor
He wants a 144 Hz monitor and Asus monitors have a good reputation. A bit on the spendy side, but he doesn't plan on buying a new one for a long time.

CyberPower - CP1500PFCLCD UPS
I've never shopped for a quality UPS before, so I'm deferring to Outer Vision's recommendation of an at least 1,000 VA rated UPS. The CyberPower I've picked out has a load capacity of 900 W and a rating of 1,500 VA. It's more than I was looking for, but a cursory search for something around 1,000 VA and 700 W only turned up UPS that were either quite a bit more expensive or didn't provide an actual sine wave as required by the PSU. This one has decent reviews and should be enough to handle occasional power flickers and give enough time to gracefully shut down in a blackout.