iMac with Retina 5K Display 2014/2015 Memory Upgrades
How to Install Memory iMac 27-inch 5K (RAM Crucial 16GB) - YouTube
How to Upgrade the Memory in the iMac Pro (late 2017) - YouTube
iMac RAM Upgrade mixing different memory sticks: 27” iMac late 2013 - YouTube
Factory Original 64GB (2x32GB) Memory Upgrade for 2020 & 2019 Apple iMac 27" w/Retina 5K Display & 2018 Apple Mac Mini DDR4 2666Mhz PC4-21300 SODIMM 2Rx8 CL19 1.2v RAM Adamanta at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET