Late 2015 - iMac17,1
Compatible upgrades for: MK462LL/A, MK482LL/A, BTO/CTO 5K 27-inch iMac
Standard RAM: 8 GB
Maximum RAM: 64 GB*
Details: By default, 8 GB is installed as two 4 GB memory modules (and two slots are unoccupied).
RAM Slots: 4
*Officially, this model supports four 8 GB modules -- one in each slot for a maximum of 32 GB of memory. However, as first discovered by site sponsor OWC, it actually will support 64 GB of memory using four 16 GB modules.