Memory RAM 1x 4GB Apple iMac Early 2009 DDR3 1066MHz SO-DIMM | E-OWC8566DDR3S4GB | APPLE \ MEMORY FOR APPLE \ OWC \ APPLE IMAC \ iMac Early 2009 \ iMac 20'' (Early
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Install memory in an iMac - Apple Support
Don't Upgrade The RAM In Your New Apple iMac, Do This Instead