Max ram for iMac.

Discussion in 'iMac' started by ImTheOne, Jan 19, 2012.

  1. ImTheOne macrumors member

    Jan 12, 2008
    Hi I have the 21.5" 2.5Ghz Quad Core i5 model of the iMac, I have seen 2 different options on Apple's website about this, and was just wondering if maybe you guys could clear it up. My iMac came with 4GB of ram, according to the Specs when I bought it, it said 8GB was max, however I just looked at Apple's instructions on replacing ram and it said the max ram for my iMac was 16GB. So which is it??
  2. Sandman1969, Jan 19, 2012
    Last edited: Jan 19, 2012

    Sandman1969 macrumors 6502a


    Nov 5, 2007
    I believe it is actually 32gb, but you have to buy 4 8gb chips. Which apple do not have as an option at their site. I think they have had 4 slots for a bit.

    If you go to and find your model that will be the max.

    What year is it? I am guessing it is a 2011 based on 2.5 i5. That will max at 32gb with 4x8gb. I would recommend going 16gb with 4 x 4gb. Since the 8gb are MUCH more costly.
  3. mmomega macrumors demi-god


    Dec 30, 2009
    DFW, TX
    16GB for 21.5, 32GB for 27 for Mid 2010 models and up

    16GB for late '09's
  4. Spike88, Jan 19, 2012
    Last edited: Jan 19, 2012

    Spike88 macrumors 6502a

    Jan 25, 2010
    Obtain / confirm the exact model (year) of your iMac. Then, use OWC site and "Drill down" to confirm MAX memory for your specific model. re:

    Then, decide to buy from OWC or from your local computer store.
  5. GGJstudios macrumors Westmere


    May 16, 2008
    You can find specs on all Apple products, including maximum RAM:
    • By visiting Actual Maximum RAM
    • By using Mactracker
    • By entering your serial number here to find specs for your model. (Be aware that some models can use more RAM than Apple shows. Check EveryMac or MacTracker to verify.)
  6. Applefan17 macrumors member

    Jan 15, 2012
    The known maximum for the model your speaking of (iMac mid-2011) is said to be 16GB of RAM. Going any higher may lead to some problems so I do recommend not adding any more past the limit. 16GB of RAM should be plenty for most people provided you don't plan on any large-scale 3D work or something of the like.
  7. theSeb macrumors 604


    Aug 10, 2010
    Poole, England
    What problems?
  8. Applefan17 macrumors member

    Jan 15, 2012
    Not so much problems with their machines, but rather complications with installing the RAM itself. Some people report the system doesn't pick up any new RAM they put in past the limit but this is just a case by case basis and doesn't usually affect most people.
  9. ImTheOne thread starter macrumors member

    Jan 12, 2008
    Mine is the mid/late 2011 version. I just got it in December.
    So according to the OWC website, I can technically have 32GB? See when I was ordering the iMac I thought that 8GB was max and that the benefit of upgrading the CPU to the 2.7Ghz was not only the increased speed but the ability to upgrade to 16GB of ram, I thought they maybe put a new mobo that had 2 additional slots, so basically they put that to make you THINK you need to upgrade to the next CPU up. That makes sense I guess.

    I am actually an IT guy and I use my computer to run multiple virtual machines for multiple different things so, the massive amount of ram is nice, glad they have realized that some people need more then 4GB of ram.

    Thanks all for the replies, I will most likely stick with 16GB of ram as it is only 100$ and 32GB is 600$ and not worth that to me!

    Also I did have one other question, before spending my money, can you mix and match the ram like you can in a PC, for instance, as long as you have matching pairs will it function properly. Like, say I wanted to order 16GB of ram, but in 2x8GB and not 4x4GB, and I moved the 2 8GBs to the first two slots and moved my original 2x2GB to the other 2 slots, would it register and run as 20GB of ram? Or does it only recognize all the same size sticks?
  10. tyche macrumors 6502

    Jul 30, 2010
    The DIMMs don't all have to be the same size. You'll get 20GB.
  11. GGJstudios macrumors Westmere


    May 16, 2008
    That's not true. Unless the wrong RAM is used or not installed properly, installing the true max of 32GB does not cause problems.
    That is due to either the wrong RAM or faulty installation, and does not have anything to do with the iMac being able to use more than 16GB.
    Yes, you can. Read my first post in this thread.
    You can mix any size sticks. There is a slight performance boost from using matching pairs, but all pairs don't have to be matched.

    MR Guide to Matched RAM on Intel Macs

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