While the 21.5-inch version makes it almost impossible to access the memory
Apple is going to extremes with its latest generation of iMac computers regarding memory upgrades. Users have (so far) been accustomed with unscrewing a metal plate to swap the RAM, but the newest iMacs require completely different actions to remove and / or exchange the memory modules.27-inch is the way to go, if you’re already determined to buy one of the new iMacs. Three reasons: insanely-large screen real-estate; a speedier CPU; and user-upgradeable RAM.
In releasing its late 2012 all-in-ones, Apple failed to point out a pretty important detail about the systems’ technical specifications – RAM upgradability.
The high-end version boasting a 27-inch display and a 2.9GHz quad-core Intel Core i5 offers an easy-access gate on the back, between the air vent and its power plug (as the image above shows, courtesy of CNet).
Remove the power cable and push the small button above the plug, and the memory bank pops open leaving the RAM modules exposed for easy swapping.
Apple ships the computer with two 4GB modules for a total of 8GB of memory, but the company says you can upgrade it with as much as 32GB of RAM.
Apparently, there’s room for only two slots, which means you need two 16GB modules to max out the RAM on your new iMac.
On the 21.5-inch configuration, it’s not as easy. In fact, it’s almost impossible for a regular user to come home with brand-new DIMMs and slide them inside the computer. Why? iFixit explains it best (in their recent iMac teardown):
“Good news: The iMac's RAM is 'user-replaceable.' Bad news: You have to unglue your screen and remove the logic board in order to do so. This is just barely less-terrible than having soldered RAM that's completely non-removable.”
So while iFixit debunks rumors of Apple having soldered the RAM to the iMac’s logic board, the hardware experts confirm that it’s almost impossible for a non-technical user to upgrade the RAM on a 21.5” iMac (Late 2012) configuration.