iMac 2009 to 2011 (A1311/A1312) Upgrade Guide – MacintoshMen
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 :
922-9385 Apple CPU Fan for iMac (21.5-inch Mid 2010) iMac (21.5-inch Mid 2011)
What Does It Take To Upgrade a 2012 iMac 21.5"?
Apple iMac 21.5" - Early 2010 Reviews, Pros and Cons | TechSpot
Upgrade iMac Intel Core i3 CPU to Core i7 - iFixit Repair Guide
Upgrading the processor on a mid-2010 iMac | MacRumors Forums
2010 iMac CPU Upgrade - The whole process - YouTube
Upgrade iMac Intel Core i3 CPU to Core i7 - iFixit Repair Guide
3.2GHz Intel Core i3 (i3-550) CPU – Apple iMac 21.5″ A1311 (Mid 2010)