Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Apple Officially Confirms 21.5” iMac RAM Is Non-User-Replaceable
64GB 32GB 16GB RAM UPGRADE for Apple iMac 27" 2012 2013 2014 2015 2017 2019 2020 | eBay
2012 21.5-Inch Apple iMac Review: Slim, Sleek, And Stylish, But Far From Shallow | TechCrunch
Apple's 27" iMac Late 2012 model. How to upgrade the ram to 16GB - YouTube
Install memory in an iMac - Apple Support
How to Upgrade iMac RAM: 2012-2020: EveryMac.com
A-Tech 16GB (2x8GB) PC3-12800 DDR3 1600MHz RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET