OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
Don't Upgrade The RAM In Your New Apple iMac, Do This Instead
OFFTEK 1GB Replacement Memory RAM Upgrade for Apple iMac 1.83GHz Intel Core Duo - (17-Inch) (DDR2-5300) Desktop Memory at Amazon.com
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider