Amazon.com: OWC 64GB (4 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with 27" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S64S) : Everything Else
Install memory in an iMac - Apple Support
Best arrangement of stock and 3rd party RAM? - iMac Intel 27" Retina 5K Display 2020 - iFixit
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
512MB (2 X 256MB) Memory for original Apple iMac G3 tray loading SODIMM RAM | eBay
Mac RAM Upgrade, Best iMac Memory Upgrade – Best Reviews
How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac
iMac RAM Upgrade mixing different memory sticks: 27” iMac late 2013 - YouTube
How To Upgrade the RAM on the New 27-Inch iMac (2020) & Save Money! $$ - YouTube
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider