Parts he used:
Intel i7-7700K CPU - http://snazzy.fm/7700k
Crucial MX300 2TB SSD - http://snazzy.fm/mx300
PC4-19200 260-pin RAM - http://snazzy.fm/imacram
OWC Thermal Sensor for SSD - http://snazzy.fm/owcsensor
iMac Display Adhesive Kit - http://snazzy.fm/adhesivekit
SSD Bracket - http://snazzy.fm/hddbracket
iMac Opening Tool - http://snazzy.fm/imacwheel
Footnote #1: I actually bought the mid-grade model. At the time, I wasn’t sure the CPU coolers were the same across all 27” models. I have since learned that they are; so if you buy the cheapest 5K iMac, you can do all the upgrades I mention in this video without issue.
Footnote #2: This is not an instructional disassembly video. I recommend checking the guides on iFixit. They are well illustrated—provide adequate caution and warning for tricky areas—and have a community section where people provide advice. At the time of this video, there is no updated guide for the 2017 iMac; however, it's very similar to the 2014-2015 A1419 model. The only big difference is the screw placement on the motherboard. Just take your time finding all of the screws (one is hidden through the gold hole in the middle of the board) and you'll be fine.
Footnote #3: A little drama that wasn't included in the video is that the first time around, the CPU got bumped out of the socket when I screwed in the cooler, so the CPU wasn't seated correctly and the computer didn't boot. Upon disassembling the machine again, I saw the CPU was out of the socket and partially bent. I bent the CPU back (silicon bends easily without damaging, luckily), reinserted it into the socket, and was more careful when I tightened the CPU cooler the second time. It's easy to wiggle the CPU out of place when installing the cooler, so be careful—and if it feels too hard to tighten the CPU socket, stop—something is wrong.
Footnote #4 - My machine's GeekBench results: http://browser.geekbench.com/v4/cpu/3...
The 27" 5K iMac is a good computer for many; however, to users that want high-end specs, Apple charges way too much money. Snazzy Labs pulls apart a base model iMac, upgrades the CPU, SSD, and RAM; showing the world the best iMac that Apple doesn't sell! Get the world's best iMac configuration for $2,000 less than what Apple charges.