Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot
Can you upgrade the RAM in the 27-inch iMac? | iMore
A-Tech 8GB RAM for Apple MacBook Pro (Mid 2012), iMac (Late 2012, Early/Late 2013, Late 2014, Mid 2015), Mac Mini (Late 2012) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
How to Upgrade Memory in a 27-inch iMac (Late 2012-2013) iMac13,2 and iMac14,2 - YouTube
16GB (2x8GB) RAM Memory Upgrade For Apple iMac 27'' A1419 Late 2012 2013 | eBay