OWC Memory Upgrades for 2017 iMac 27-Inch 28 Jun 2017 Upgrade the memory of your 27-inch 2017 iMac up to 64GB. OWC memory kits are 100% Apple compatible and backed by a lifetime OWC warranty. 64GB of RAM in the new iMac costs $600 currently Source: Memory Upgrades for 2017 iMac 27-Inch