Apple iMac A1311 Mid 2010 Core i3 8GB RAM 500GB - OS X EL Capitan | eBay
Is it worth it to upgrade RAM on Mid 2010 21.5 iMac? | MacRumors Forums
Install memory in an iMac - Apple Support
NEMIX RAM 32GB (4x8GB Upgrade) DDR3-1333 PC3-10600 204-Pin SODIMM Memory for Apple MacBook Pro Early/Late 2011, iMac Mid 2010 27 inch 4-Core, iMac Mid 2011 21.5/27” , Mac Mini Mid 2011 at Amazon.com