Can I put 32GB ram on my iMac when max is 16GB?

Discussion in 'iMac' started by yoricardo, Oct 3, 2015.

  1. yoricardo macrumors member

    Jun 24, 2010
    I have a 21.5 inch iMac, mid 2011 model. It has been running slow so I decided to buy some extra memory from On their website it says that you can install 32gb of ram on my model and so I went ahead and bought it and have just installed it.

    Only after installing it did I have the idea of seeing what it says on the Apple website (yes, backwards thinking, I know) and on the Apple website it says the max for my model is 16gb.

    The question is, now I have 32gb, as advised by Crucial, should I just leave 32gb in my machine, or could it damage my Mac?

    I appreciate I can call Crucial and they'll sort it out, but I'm interested to know what the implications are of over-speccing the computer.

  2. SandboxGeneral Moderator emeritus


    Sep 8, 2010
    Your model is good with 32 GB of RAM and there is nothing to worry about.

    MacTracker shows its capable of 32 GB, while Apple, often understates what their computers are capable of.

    Screen Shot 2015-10-03 at 7.39.55 AM.png
  3. throAU macrumors 603


    Feb 13, 2012
    Perth, Western Australia
    Most likely, the Sandy Bridge and later chipset supports 32 GB of RAM.

    Apple frequently lists the max RAM capacities as lower than they really are, as I believe they only list what they had on sale as the 'max'.

    Back in mid 2011 or so, 8 GB DIMMs (required for 32 GB - x4) were about $800 each (i.e., 32 GB would have cost $3200, you would have been far better off just buying a Mac Pro to get 32 GB with much cheaper 4 GB DIMMs by using more slots that it has available), so that was a very very expensive option that Apple did not offer.
  4. yoricardo thread starter macrumors member

    Jun 24, 2010
    Very interesting, many thanks.

    Will I actually get an improved performance over 16GB, however, or is there nothing possible over and above that amount?
  5. SandboxGeneral Moderator emeritus


    Sep 8, 2010
    I highly doubt the extra RAM will be noticeable for you, unless you're doing many, many, RAM intensive tasks at the same time.

    The slow down you're experiencing is probably due to the hard drive in there. If you upgrade to an SSD, that's when you will see an improvement by orders of magnitude.
  6. throAU macrumors 603


    Feb 13, 2012
    Perth, Western Australia
    Depends what you're doing. More RAM is a case of diminishing returns unless you are running something that needs it.

    If you're just doing regular "Stuff" then probably not. If you're running an SSD then less likely.

    But if you are working with large video files, multiple large images in photoshop, other operating systems in virtual machines, etc. then more RAM will be useful.

    You can perhaps check out the memory pressure graph in activity monitor and see how bad it is when you have a typical "large" workload running.

    For most people 16 GB is plenty (hell, 8 GB is plenty for most, especially with an SSD), but you may be different. I did notice a general speed up on my 15" MBP going from 8 GB to 16 GB with a hard drive, but it was nowhere near the difference between 4 GB and 8 GB for general use. It was like 10% of the improvement if that when doing basic stuff, and that was due to hard disk cache. SSD in the box, and that improvement won't be significant.

    Going from 16 GB to 32 GB for general non-ram-intensive stuff will be even less noticeable. If you've got 16 GB and a hard drive i would suggest your best bang for buck upgrade would be an SSD.
  7. dogslobber macrumors 68040


    Oct 19, 2014
    Apple Campus, Cupertino CA
    This type of machine runs great with 32gb of ram. In fact, it's the last 21.5" iMac to be able to do that as 2012 onwards only had two dimm slots.
  8. Sirmausalot macrumors 6502a


    Sep 1, 2007
    On trick to get great performance out of an older Mac is to upgrade to an SSD-- and the trick part is to use an external SSD and use it as a boot drive for the OS and all of your programs. That way you don't have to open the machine up. A much, much better investment than more RAM after 16GB...
  9. fastlanephil macrumors 65816


    Nov 17, 2007
    You can run Apple's Activity Monitor(it's in the utilities folder) to see how much memory you're using and how much headroom you still have. It also checks CPU and disk use.
  10. rkaufmann87 macrumors 68000


    Dec 17, 2009
    Folsom, CA
    32 will be fine but totally unnecessary .
  11. throAU macrumors 603


    Feb 13, 2012
    Perth, Western Australia
    Yeah the kinda fuzzy thing is that with a spinning disk, more RAM will help with caching a fair bit, but much more than 16 GB the benefit of that becomes more and more dubious... a complete base install of OS X is about 10 gb from memory, there's only so much more caching can do.

    I'd say if you're running 16 GB and a spinning disk you'd probably want to be upgrading to SSD as a priority. RAM will of course help by caching, but the stuff has to get into memory in the first place from the disk somehow and that part will still be slow...

    Again, not to say 32 GB won't help... just probably not as much as an SSD. If that makes sense.
  12. yoricardo thread starter macrumors member

    Jun 24, 2010
    Very interesting suggestion re upgrading to an SSD. Which one would you recommend so I can work out a cost/benefit comparison?
  13. randalf72 macrumors member

    Apr 25, 2014
    I've had good experiences with the Samsung 840Pro and the new 850 seems to be a whole order of magnitude cheaper with very similar performance/warranty specs to the 840Pro.

    UK Prices, which I accept may give a false idea (due to us getting ripped off by everyone when it comes down to computer gear) are roughly £115 for the 500gb version inclusive of all taxes, so maybe around $150 in the US?
  14. tomilchik macrumors newbie

    Feb 4, 2016
    It really depends. I just upgraded memory on my iMac 27" mid-2011: added two 4GB units to the existing 2x2GB to the total of 12GB.
    Immediate effect: it seems that Safari and Mail come up faster. But that's the perceived, not measured.
    Now - concrete #'s:
    with the following apps running - Safari (8 tabs), Mail, Activity Monitor, LogicPro X, Photos - I see these figures:
    - Memory Used: 6.40GB
    - Cache: 4.65 GB (it is my understanding that Cache is not *part* of Memory Used, but *in addition to*).
    - Swap Used: 0

    Altogether: iMac happily sucked into memory close to 11GB of stuff => much less disk I/O (I wish I had kept track of Disk I/O before I installed the upgrade). This to me is another benefit of more RAM: not only things come up and run faster - disk works less, and perhaps will live longer.

    I didn't want to risk throwing too much money away based on semi-official info that my iMac can take 4x8GB=32GB. But I am very likely to replace my original 2x2GB=4GB with 2x4=8GB to the total of 16GB. And regret not upgrading to 32GB if/when someone comes up with convincing confirmation of 1)successfully upgrading, and 2)seeing iMac actually using all 32 (or at least beyond 16)
  15. Samuelsan2001 macrumors 604

    Oct 24, 2013
    You would still be better off performance wise with a SSD over RAM......
  16. tomilchik macrumors newbie

    Feb 4, 2016
    If you mean "upgrading HD to SSD" vs "upgrading RAM to bigger" - then yes, agree.

    Money-wise: SSD comes out much cheaper per 1GB - about $0.5/GB (1TB for $500); RAM - mine cost me ~$7/GB ($56 for 8GB). One-time cost with SSD will be higher, and upgrade/installation is more complicated - not everybody will have guts to do it at home, and a comp shop will charge whatever they charge (I saw someone mentioning $100).

    So in the end it boils down to how much people want to spend on what kind of performance improvement. $60 for somewhat noticeable improvement; or $200-500 for very noticeable.
  17. Jody Verall, Mar 28, 2016
    Last edited: Mar 29, 2016
  18. off_piste macrumors 6502a

    Oct 25, 2015
    I put 32 gb of ram in my mid 2011 iMac. The system recognizes it even though it claims a max of 16. Doubt it was necessary but that's never stopped me from pointlessly upgrading in the past.
  19. DaCraftyFox macrumors newbie

    May 10, 2017
    Hello all!

    I've upgraded my 27 iMac mid2010 from 8g to 32gb, mainly because I work with some huge files in photoshop from time to time.

    The thing is, also from time to time, I get multiple crashes... and then it reboots to this:


    I can insert here one or the reports that the system presents me after the reboot. It really is annoying once it can crash and reboot every 2 min... for one day, or 2 or 5... And then, it keeps running perfectly for months.

    Any ideas?
  20. Richdmoore macrumors 68000


    Jul 24, 2007
    Troutdale, OR
    I have the exact same Mac, and am running 32g without issues.
  21. redheeler macrumors 604


    Oct 17, 2014
    Try running Apple Hardware Test to see if your RAM passes. I was having crashes & kernel panics on my 5K iMac like you described, and it turned out the RAM failed the test. Returned/replaced the defective RAM and it now works just fine.
  22. kiwipeso1 Suspended


    Sep 17, 2001
    Wellington, New Zealand
  23. briloronmacrumo macrumors 6502


    Jan 25, 2008
    Have seen the same scenario redheeler describes. Most likely the Ram is causing the kernel panics. Another tool to check Ram is MemTest
  24. nambuccaheadsau macrumors 68000


    Oct 19, 2007
    Nambucca Heads Australia
    Only buy memory from Mac Specialists. Crucial and OWC for mine.
  25. cynics macrumors G4

    Jan 8, 2012
    I found if you have a HDD if you stuff a lot of RAM into it and leave it on all the time it's stays fairly quick. I don't notice any slow downs or beach balls.

    However after a fresh reboot it's a turd. An SSD will make a bigger difference in everyday task then any other upgrade (unless you are doing very specific task like after effects).

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27 October 3, 2015