OWC 32GB (4 x 8GB) PC14900 DDR3 1866MHz SO-DIMMs Memory Compatible with 2015 (Late) iMac 27" w/Retina 5K Models and Compatible PCs (OWC1867DDR3S32S) at Amazon.com
What RAM (Memory) Is Compatible With My Motherboard?
Understanding Motherboard and RAM Compatibility | Crucial.com
Can I plug a DDR3 RAM stick into a DDR4 motherboard socket? - Quora
What is the difference between DDR3 and DDR4 RAM?
memory - Is DDR4 RAM compatible in a DDR3 RAM slot? - Super User
OWC 4GB PC8500 DDR3 1066MHz SO-DIMM Memory Compatible with Early 2009, Early 2010 MacBook, MacBook Pro Unibody Models, 2009/2010 Mac Mini, and 2009 iMac Models at Amazon.com