OWC Tears Down 21.5-inch iMac Retina 4K, Confirms Memory Is Soldered


Along with the newly released 27-inch iMac with Retina 5K display released by Apple today, we also got our hands on the brand new 21.5-inch iMac with Retina 4K display.

Check out the gallery below to see what we found when tearing down the Late 2015 21.5-inch iMac.

Some noteworthy observations from the teardown:

  • Model name: iMac (same model name as 27”)
  • Model ID: iMac16,2
  • Memory is soldered in. OWC recommends buying as much memory as you can at the time of purchase to increase the longevity and usefulness of your iMac.
  • CPU is soldered in.
  • New keyboard is interesting. A lot of things have changed size-wise. Closer to the MacBook style key, much shorter throw.
  • New mouse feels the same (likely the goal).
  • 4K Retina display looks just as great as the 5K, just smaller.
  • Notably slower startup vs. fusion drive equipped 27” iMac.
  • Two Thunderbolt 2 ports (Check out OWC’s Thunderbolt Central)

More unboxings/teardowns:
See our teardown and unboxing of the 27-inch iMac with Retina 5K display (Late 2015) here: http://blog.macsales.com/33572-owc-unboxes-tears-down-the-late-2015-27-inch-imac-retina-5k

OWC has a great selection of portable and desktop drives. And be sure to check out our Thunderbolt Central page for high performance Thunderbolt solutions.


  • Sorry if this question is already answered. I have an Imac 21.5 late 2015, i7 3,3 ghz 16 gb ram and 1tb fusion drive and I want to know if it is possible to upgrade the fusion drive(maybe the HDD part) to a SSD?

  • If we have an 8GB RAM unit, is it possible to get 16GB in it after the fact?

  • If I replace the 1TB HDD with a 1TB SSD will I have the same problem with the fans going full speed as with the 27″?

  • If you go for the 2TB fusion drive, is the SSD still paired with a 5400-RPM drive? How’s the performance of this for digital audio compared to using a 7200 RPM drive (non-fusion)? The same, better, slower?

  • It seems that iMac 4k (with normal hard drive)does not have a PCI-E inteface to install nvme SSD.
    with Fusion Drive version does have a PCI-E interface to load nvme SSD.

  • Shocking: In the purchase process…
    Choose Storage
    Click: How much storage is right for you?
    will show:


    1TB Fusion Drive pairs a 1TB hard drive with 24GB of fast flash


    — enough to store important OS X files and applications to ensure fast startup, near instant wake from sleep and quick application launching, with room left over for your most frequently used files and apps. The 2TB and 3TB Fusion Drives pair a larger hard drive with 128GB of fast flash storage, providing even more space for your most frequently used files. For the best performance, iMac systems with 32GB of memory should be configured with a 2TB or larger Fusion Drive or all flash storage.

  • The new iMac’s use the Z170 chipset?

  • Can the 21.5″ 4k iMac’s hard drive be replaced/upgraded from the stock 5400rpm hard drive? I was thinking of putting in a 7200rpm hard drive or flash drive on mine. Thanks.

  • What is the real-world speed of the new 2015 Apple 21.5-inch iMac SDXC reader? Does it support UHS-II Maximum Speed (300 MB/s read/write)?

    • This is not planned obsolescence.
      This is building an iMac that will last for a decade.

      There are few parts that can go wrong. It will last way beyond the useful life of Windows PCs.

      For example, I’m still using a MacBook Pro 17 from 2006. This is the non-core Duo Model. Sure, it is no longer supported by the latest OS, but it still runs great. It’s CPU is also soldered in. That is 8 years of life and going.

      Macs last so long, I have 11 in use at home. I can have one in every room of the house. I keep 5 working on my desk. Each can be dedicated to running certain tasks – talk about multitasking. Only my PowerPC models have been retired – though they still run well. I keep a shelf full of them. I just don’t have the desk space nor need for more multitasking.

      • So what yoi’re saying is that your older macs, with slotted RAM at least, lasted that long anyway?

        This is Apple blatantly hating on the consumer. Pleeenty of space for a couple of RAM slots in there. They sure haven’t done it to save us money!

      • You’re right. Macs last so long. I’ve had my MBP 15″ since 2005 and it runs well. But after a decade, I need another computer. I am now planning on an iMac 21 retina with 16gb memory and 256gb flash storage.

        My question is, since I keep my computer for so long, will I be able to later increase my flash storage to 512gb or is the area ‘soldered’ as well?

        • Hello Cece,

          Thank you so much for your question. The PCIe SSD will not be soldered in. However, at this time there are no available SSD upgrades.

          If you have any further questions, please contact our Technical Support Team!

          • I’m a little confused. In an earlier reply, you said that any 2.5″ SSD or HDD can be used. I’m also new to all this, but the HDD you pulled from the unit is SATA? I see many 2.5″ SATA SSD’s online – does this mean I can just pull the HDD and replace it with one I purchased?

            • Hello dmp,

              Thank you for your question and sorry for any confusion. At this time you can only add/upgrade a 2.5″ SATA HDD or SSD into the main (SATA) bay.

              If the 4K iMac was purchased with a Fusion Drive or SSD, they will also have a PCIe based connection. However, at this time there are no compatible PCIe SSD upgrades.

              *Please note that if the 4K iMac was only purchased with a HDD, it will not have the PCIe connection.*

              If you have any further questions, please contact our Technical Support Team!

              • hello, I just bought an iMac 16,2 with an SSD 250GB (i7 quad core 3.3ghz) and an MBP 15″ i7 quad core 2.8 ghz 500GB SSD. Since both are PCIe, is the new PCIe SSD 1TB upgrade will be available for the iMac?
                Thanks for your answer

                • Hello Serge Q,

                  Thank you for your question! At this time we do not offer the compatible PCIe SSD for the iMac 16,2. We are always looking to have the most up to date upgrades. Please keep up to date on new product releases by signing up for the OWC Newsletter!