Upgrading RAM On The New 27-inch iMac Is Easy, Here's How | Cult of Mac
Apple iMac (Late 2012) review (21.5- and 27-inch) | Macworld
iMac (27-inch, Late 2012) - Technical Specifications
27" iMac Offers Easier RAM Upgrade
A-Tech 8GB Kit (2x4GB) 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
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)