RAM & Memory Upgrades
32GB (4 x 8GB) DDR3 1600MHz PC3-12800 204-PIN SODIMM MEMORY RAM KIT COMPATIBLE WITH INTEL IMAC 27" (LATE 2012 - LATE 2013)
SIZE/CAPACITY: 32GB KIT (4 x 8GB) VOLTAGE/POWER CONSUMPTION: 1.35v CAS LATENCY: CL11 SPEED: PC3-12800 (1600MHz) TYPE/INTERFACE: 204-PIN DDR3 SODIMM 204-PIN INTEL IMAC & INTEL MAC MINI DDR3 SODIMM
https://www.bizrate.co.uk/ram_memoryupgrades/32gb-4-x-8gb-ddr3-oid5216989313.html