Additionally, the new iMac actually has a "socketed" CPU that can also be replaced. It's been even longer since that's been the case in a 21.5-inch iMac -- 2012, to be exact. Of course, we need to be clear that these are not easy-to-access parts. You'll need to pry the case apart and remove the screen entirely. That's not what I'd call "user-serviceable," and Apple agrees. If you start tinkering with these parts, you'll almost certainly void your warranty. That said, it's good to know that if you pick up one of these iMacs and it starts to get sluggish a few years down the line, you'll have options -- assuming you're brave enough to pull the iMac's screen off.