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How to Upgrade the Main Drive in a 21.5-inch iMac 2017

The Rocket Yard and have long encouraged the do-it-yourself philosophy when it comes to upgrading your devices. And with our extensive catalog of instructional videos, we help make it possible for users to perform the upgrades they need themselves.

We are always working hard to expand our catalog of step-by-step instructional videos, and after adding a video demonstrating how to install memory in the new 2017 21.5-inch iMac with Retina 4K display, we’ll now show you how to upgrade the same model’s main drive.

Related: Rocket Yard Guide: iMac DIY vs. Apple Repair

Upgrade beyond the factory 2.5-inch 1.0TB hard drive ceiling and install a hard drive up to 3.0TB, or for the ultimate performance upgrade, swap the main hard drive out with an SSD up to 2.0TB. Utilize our install video to guide your upgrade step-by-step and make your iMac faster than from the factory.

Note: Professional installation is recommended for this upgrade due to the complicated process.

Fusion Drive Note: If you’re upgrading a Fusion Drive equipped iMac you will need to disable the Fusion Drive first, and then, if desired, create a Fusion Drive with the new drive after the upgrade is performed. You can learn how to do that at…

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  • Thanks for this video. It’s easily and clearly explained. I bought my iMac in March of last year for school. Just as I bought mine the 2019 models came out. Those models are self-upgradable by panels now apparently.

  • Wanted to upgrade the Fusion drive from 1TB to 2TB in the 21.5″, 3.4GHz, as you can in the 27″, 3.4GHz iMac. Apple say that this cannot be done pre sales as it is not an option on 21.5″ Why? Is it easy to replace the Fusion drive in the 21.5″?

  • So, does this hard drive upgrade not require the adapter used in the slightly older iMac to account for the Apple firmware heat sensor issue?

  • Is the controller seriously limited to just 3TB???? With 4TB to 10TB drives readily available, is this really a hard limitation?

    • never mind; just realized these are 2.5″ drives. Another reason I’ll never buy an iMac. If I want a laptop computer with expensive, limited, lower-performing laptop components, I’ll buy a laptop.

      • The small iMac takes 2.5″ drives, but the larger version (27″) takes 3.5″ drives so you can go high-capacity if you want. The best thing about these is adding the additional SSD and making a fusion drive, so you end up with a super-fast machine as well as tons of storage. But as for the little 21.5″ iMacs, because you’re replacing a laptop drive, the gains from going SSD are really impressive. I’ve upgraded lots of these for my clients, they’re always amazed at how much faster their Macs are than even when they were new!

      • Nathan, when you throw out an application on a Mac you can still land up with files you don’t need. But if you get a piece of software like AppTrap, which is what I use, your Mac will ask if you want to throw out other files associated with the application you are getting rid of. AppTrap is free. Look for it on

      • My iMac isn’t lower performing and wasn’t overly expensive. Your comment is one of a straw man argument.