Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else
Upgrading a 27-inch iMac 5K to 14 terabytes - Replacing the Fusion Drive with both a SSD and an harddisk
Install memory in an iMac - Apple Support
How to Upgrade the Memory in the iMac Pro (late 2017) - YouTube
Amazon.com: OWC 32GB (4x8GB) 2400MHZ DDR4 SO-DIMM PC4-19200 Memory Upgrade Compatible with 2017 iMac 27 inch with Retina 5K Display (OWC2400DDR4S32S) : Everything Else
Memory Upgrades for 2017 iMac 27-Inch
Can you upgrade the RAM in the 27-inch iMac? | iMore
Apple iMac (27-inch, 2017) review: Apple doesn't mess with success - CNET
iMac Retina 5K: Memory upgrade (RAM)
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac
Install memory in an iMac - Apple Support
How to upgrade the 27-inch 5K iMac (2019) with a massive 128GB of RAM [Video] - 9to5Mac