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
How to Upgrade iMac RAM (20" and 24" Aluminum): EveryMac.com
DDR3 RAM for Late 2009 iMac | MacRumors Forums
Imac 2009 Ram Upgrade Sale Online, 56% OFF | ilikepinga.com
Imac 2009 Ram Upgrade Sale Online, 56% OFF | ilikepinga.com
SOLVED: Late 27" iMac 2009 recognizes only 2 ram slots. The saga continues... - iMac Intel 27" EMC 2309 and 2374 - iFixit