Review: 27-inch iMac with Retina 5K Display – Six Colors
Upgrade your iMac's RAM in less than 5 minutes - YouTube
iMac with Retina 5K Display 2014/2015 Memory Upgrades
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