New iMacs and the RAM situation...
Install memory in an iMac - Apple Support
upgrade - Optimal Memory Layout for Late 2015 iMac - Ask Different
New 21.5-inch iMac least repairable yet due to lack of RAM, hard drive upgradability - 9to5Mac
iMac (Retina 5K, 27-inch, Late 2015) optimal RAM layout | MacRumors Forums
Adamanta 16GB (2x8GB) Compatible with Apple Late 2015 iMac 27" DDR3L 1
upgrade - iMac 27" Late 2015 - what ram to buy? - Ask Different
Amazon.com: Late-2015 Apple iMac with 2.8GHz Intel Core i5 Quad-core (21.5-Inch, 8GB RAM, 1TB) (Renewed) : Electronics
Logic Board 3.3 GHz i7 16GB Ram iMac Retina 4K 21.5" Late 2015 A1418 W - Part Haven
Timetec 8GB Compatible for Apple Late 2015 iMac (27-inch w/Retina 5K Display) DDR3L 1867MHz / 1866MHz PC3L-14900 2Rx8 CL13 1.35V 204 Pin SODIMM Memory Module MAC RAM Upgrade for iMac 17,1 at Amazon.com
Apple iMac Retina 4K 21 .5 inch Late 2015 2.8GHz i5 16GB RAM 1.02 Fusión drive | eBay
Consomac : iMac 21,5'' 4K 2017 : la mémoire vive n'est plus soudée !
iMac 21.5" 4K 2019 | 8GB RAM / 256GB SSD | Tech to School
How to Upgrade/Install Memory in a 21.5-inch iMac (Late 2012– Mid 2014) iMac14,1 iMac14,3 - YouTube
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Apple iMac 27-Inch Retina 5K Core i7 4GHz 32GB RAM 1TB SSD (Late 2015) | Reverb
iMac Intel 27" EMC 2806 (Late 2014 and Mid 2015, 5K Display) Memory Maxxer RAM Upgrade Kit
DDR3 12800 RAM 16GB (2x8GB) - 27" iMac with Retina 5K Display (Late 2014, Mid 2015, Late 2015) - 64GB MAX - Best Deal in Town Las Vegas
A-Tech 32GB (4x8GB) RAM for Apple iMac Late 2015 27 inch Retina 5K | DDR3L 1866MHz / 1867MHz PC3L-14900 1.35V 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
A-Tech 16GB (2x8GB) RAM for Apple iMac Late 2015 27 inch Retina 5K | DDR3L 1866MHz / 1867MHz PC3L-14900 1.35V 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
OWC 32GB DDR3 1867 MHz SO-DIMM Memory Kit OWC1867DDR3S32S B&H
