3.2GHz Intel Core i3 (i3-550) CPU – Apple iMac 21.5″ A1311 (Mid 2010)
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 :
Apple iMac 21.5" - Early 2010 Reviews, Pros and Cons | TechSpot
Apple iMac 21.5" A1311 Logic Board 820-2784-A W/ CPU i3 3.06Ghz 2010 Free ship | eBay
21.5" iMac Mid 2010 // $345 - Boulder Mac Repair
2010 iMac CPU Upgrade - The whole process - YouTube
Upgrade iMac Intel Core i3 CPU to Core i7 - iFixit Repair Guide