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iMac 21.5 Mid 2011 with 2 - 2GB ram sticks My iMac currently has two - 2GB ram sticks. One in each slot and two empty slots. If I want to keep what I have and also add additional ram does the ram have to be a match to what I have or can I also add two - 4GB ram sticks for a total of 12GB ram?
I would install in pairs. Add with two 4’s or two 8’s. Here’s how to do it: iMac Intel 21.5" EMC 2428 RAM Replacement Standard RAM: 4 GB Maximum RAM: 32 GB* Details: By default, 4 GB of RAM is installed as two 2 GB SO-DIMM modules. Two slots free. *Officially, this model supports four 4 GB modules – one in each slot for a maximum of 16 GB of memory. However, third-parties have discovered that it actually will support 32 GB of memory using four 8 GB modules. RAM Type: PC3-10600 DDR3 Min. RAM Speed: 1333 MHz PC3-10600 4 GB RAM Chip PC3-10600 2 GB RAM Chip PC3-10600 8 GB RAM Chip