How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
Apple Imac 20" Early 2009 A1224 Intel Core 2 2.66ghz 2gb Ram El Capitan -Working | eBay
Early 2009 duo core (square mac) now running High Sierra patch from Dosdude1 flawlessly. : r/mac
8GB Kit (4GBX2) DDR3-1067Mhz for Early/Late 2009 iMac and 2009-2010 MacBook Pro at Amazon.com
8GB -2x4GB Memory Ram Upgrade 20" Apple iMac 9.1 2.66GHz Core 2 Duo Early 2009 | eBay
16GB RAM on an iMac 24" (early 2009)? - Apple Community
A-Tech for Apple 2GB DDR3 1067MHz / 1066MHz PC3-8500 SODIMM Memory RAM Module for MacBook, MacBook Pro, iMac, Mac Mini - (Late 2008, Early 2009, Mid 2009, Late 2009, Mid 2010) Models at Amazon.com
iMac 24-inch (Early 2009) Core 2 Duo 2.66GHz - HDD 640 GB - 4GB | Back Market
iMac 24-inch Early 2009 – Full Tech Specs, Release Date, and Price
OWC 6GB (2GB + 4GB) PC8500 DDR3 1066MHz SO-DIMMs Memory Compatible with Late 2008, Early 2009, Early 2010 MacBook, MacBook Pro Unibody Models, 2009/2010 Mac Mini, 2009 iMac Models at Amazon.com
A-Tech for Apple 1GB DDR2 667MHz PC2-5300 200-pin SODIMM for MacBook, MacBook Pro, iMac, Mac Mini - (Early/Mid/Late 2006, Mid/Late 2007, Early 2008, Early 2009) - Memory RAM Module at Amazon.com