Upgrade iMac Intel Core i3 CPU to Core i7 - iFixit Repair Guide
ODD & CPU above 3000 RPM iMac 27 mid 2011… - Apple Community
Apple iMac Upgrades | SimplyFixIt
HOW TO: Upgrade The CPU from an Intel Core i5 to an Intel Core i7 on a Mid- 2011 21.5inch iMac - YouTube
Further Explained: Apple's iMac 2011 Model Hard Drive 'Restrictions'
Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac(Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) MAC RAM Upgrade :