Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1067MHz / 1066MHz PC3-8500 CL7 Dual Rank for iMac (Late 2009 21.5-inch / 27-inch) SODIMM Memory MAC RAM Upgrade for iMac 10,1 and iMac 11,1 at Amazon.com
Review: Apple's 27" big screen iMac (late 2009) | AppleInsider
iMac 20-inch Early 2009 – Full Tech Specs, Release Date, and Price