iMac RAM Model ID 11,3 to 12,2 DDR3 1333Mhz
The iMac DDR3 1333 11,3 with i5 or i7 processor has a maximum of 32GB (8GBx4.) For the iMac DDR3 1333 11,3 with i3, click here. The standard RAM for iMac 12,1 has 4 slots and has a maximum of 32GB. Some popular iMac 1333 RAM upgrades would be the 16GB or 32GB configuration. A popular iMac RAM 1333 4GB option would be the 16GB (4x4GB).
The iMac 12,1 Education Model has 2 slots with a maximum of 16GB (8GBx2).
The iMac 12,2 has a maximum of 32GB (8GBx4.)
These models are also known as the iMac Mid 2010 and Mid 2011 DDR3-1333Mhz.
12GB Limitation: Many DDR3-1333Mhz 4GB and 8GB modules on the market do not meet the Apple spec, and limit you to 12GB maximum. However, using Ramjet 4GB or 8GB SO-DIMMs, you can upgrade to the full 16GB to 32GB system maximum.
Non-Stacked IC's: Ramjet uses a non-stacked module for the 4GB and 8GB DDR3-1333 module for the iMac. The cheaper stacked IC variety of SO-DIMM draws more power, which increases heat and can cause increased errors. Ramjet ONLY uses premium non-stacked chips.