HDD Upgrade on Late 2015 21.5" iMac

Discussion in 'iMac' started by 0mgjohn, Apr 9, 2017.

  1. 0mgjohn macrumors newbie


    Mar 26, 2017
    I know that Apple say the Late 2015 iMac's aren't upgradable once purchased, but I'm aware that it is possible to upgrade the storage on these devices.

    The iMac I've been given has the 1TB 5400rpm HDD, but I'd be willing to sacrifice the amount of storage for a much quicker SSD like I have in my MBP, as I a) won't need that much storage and b) find load times far too long compared to my similarly specced MBP.

    So, given I can get someone with the knowhow (or even attempt it myself) would I be able to replace the HDD with a SSD (probably 512GB) if I fit an adapter that can allow me to mount an SSD.

  2. nambuccaheadsau macrumors 65816


    Oct 19, 2007
    Nambucca Heads Australia
    Consider as others have done using a Thunderbolt or USB3 external SSD as the boot drive. You will get the advantage of the speed of the SSD without the worry of cracking your iMac open.
  3. RichardC300 macrumors 65816


    Sep 27, 2012
    Chapel Hill, NC
    You can probably do it yourself! It's pretty straightforward. I replaced the HDD in my mom's late 2013 21.5" iMac with an SSD and upgraded the RAM, and that's the same procedure as it would be on your model (minus the RAM, since yours is soldered on). If you think through the steps before you do them and go slow and have a hint of manual dexterity, it's pretty simple. You won't need any adapter, too.

  4. Fishrrman macrumors G5


    Feb 20, 2009
    Easiest and fastest -- along with safest -- way is to connect a USB3 SSD and let it become your "external booter".

    You'll realize 85-90% of the speed of an internally-installed drive, with none of the potential problems of cracking the case.

    Some of the new "ready-to-go" USB3 SSDs are so small that once you velcro them to the back of the iMac's stand, they'll be all-but invisible.

    And -- you'll still have the 1tb HDD for extra storage.
  5. cynics macrumors G4

    Jan 8, 2012
    Easiest solution however you wouldn't be able to use bootcamp from it (not sure if that even matters to the OP) and I'm not certain but you might not have TRIM support (don't MacOS support this over USB3?).
  6. Fishrrman macrumors G5


    Feb 20, 2009
    "and I'm not certain but you might not have TRIM support (don't MacOS support this over USB3?)."

    He won't have TRIM support.
    But... TRIM support is inconsequential, of no importance.

    I've been booting and running my late-2012 Mini via USB3 for more than FOUR YEARS now. The SSD it runs from benchmarks "same as new".

    The "lack of TRIM" has NEVER become an issue.
  7. estabya macrumors 6502


    Jun 28, 2014
    I don't think it is accurate to say that TRIM is inconsequential, but it definitely is not as important as it was a few years ago. Most SSD controllers these days have fairly robust garbage collection systems, so TRIM is not a necessity. It helps, but realistically you will be replacing your computer before you wear out your SSD, with TRIM or without.
  8. cynics macrumors G4

    Jan 8, 2012
    I'd probably be more curious about wear leveling and other speed factors vs seq read which is how they are typically rated.

    Obviously it doesn't need to run (you and many others aren't) and it may not present any noticeable differences (tbd) however out of curiosity I used the verbose option with fstrim on my laptop. I know for a fact it ran on Friday night because I initiated it. Its been set for a weekly trim which hasn't occurred yet since then, so ~ 3 days....


    Shockingly (for myself included) 2.5 GiB (~2.7 gb) were trimmed and I have hardly used the laptop since Friday except fairly heavy internet browsing.

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