Does my late 2012 iMac 21" support fusion drives? Back in June 2013 I bought an 21" iMac with a standard 1TB HDD. By now OWC offers upgrades for these machines in the form of an SSD expansion board, which can be used to form a fusion drive with the HDD.

However, they point out that some iMacs don't sport the slot for this. Is there any way I can find out if my iMac supports the SSD board, without opening it?
From the page you linked - 


  The initial production of the base model for the 21.5" iMac didn't come with a slot for the SSD. Later production models included the SSD slot, but there's no way to determine if the 2012 21.5" iMac with a 2.7GHz processor has the SSD slot without opening it up to see if it's available. If you have already opened the iMac up and it does have an SSD slot, this SSD is compatible.


The 2.9 &amp; 3.1 GHz machines should be compatible.