Except for the RAM in the 27 inch, Apple sealed off the iMac and retina MacBook Pro, making them almost impossible to repair or upgrade. This makes some sense in the portable rMBP, but the iMac is a desktop. Couldn't apple have made it 1/4 inch thicker so that it could be easily opened? It's ridiculous. I love the good old days where getting inside your Mac took a standard screwdriver and nothing else. Even the previous generation iMac and MBP were still relatively easy to get into.