Apple's 27" iMac Late 2012 model. How to upgrade the ram to 16GB - YouTube
NEMIX RAM 16GB Kit (2x8GB Upgrade) DDR3-1600 SODIMM PC3-12800 for Apple MacBook Pro Mid 2012 / iMac Late 2012 / iMac 2013, Late 2014, Mid 2015, Mac Mini Late 2012 at Amazon.com
CMS 8GB (2X4GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® Mac Mini Core I5 2.5 (Late 2012) - A24 at Amazon.com
A-Tech 32GB Kit (4x8GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
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
APPLE IMAC LATE 2012 27" INCH A1419 i7 3.4GHz QUAD 8 GB RAM 1 TB HD GRADE B | eBay
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Apple iMac 27" Late 2012 A1419 i5 @3.2GHz 8GB RAM 3TB MD096LL/A GTX 675MX *READ* | eBay
Apple iMac 21.5" Late 2012 Intel Core i5 2.90 GHz 1TB HDD 8GB RAM EMC 2544 A1418 | eBay
Apple iMac review (2012) | Engadget
iMac RAM for Model 13.2 to 15.1| DDR3-1600MHz | 8GBx2 | MacMemory.com
Review: 21.5-inch 2012 iMac takes two steps forward, one step back | Ars Technica
Apple iMac 27" - Late 2012 Reviews, Pros and Cons | TechSpot
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
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