mbuck2

Q: Adding memory to mid-2010 iMac

Is there a recommended layout for mounting a pair of 4GB PC3L-12800/1600MHz and a pair of 2GB PC3-10600/1333MHz cards so I get the best array and a full 12GB RAM? Notice that the speeds (1600MHz and 1333MHz) are mismatched.


Before you reply, please be very careful about terms like 'upper' and 'lower' (or 'top' and 'bottom') slot, because the Apple documentation is exactly backwards from what everybody else says and does. They clearly say here (iMac: How to remove or install memory - Apple Support) that the 'top' slots are closest to the screen, yet all other sites, blogs, videos, help files, etc that I have seen refer to the 'top' (or 'upper') slots as those highest when the computer is laying on its face...hence those closest to the STAND.


Also, please identify what is meant by the Bank0/DIMM0, Bank0/DIMM1, Bank1/DIMM0 and Bank1/DIMM1 slots. Many sites say that the largest (or fastest) chip should go in the primary slots, but they neither specify which Bank (or which DIMM) that should be, or where they are, physically.


So far, I have discovered that I cannot mix cards of different speeds, and both 1600MHz cards must go in the same SIDE, not the same upper/lower slots....which is contrary to what EVERYBODY says.


Help?

Posted on Nov 17, 2015 6:22 AM

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Q: Adding memory to mid-2010 iMac

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  • by rkaufmann87,

    rkaufmann87 rkaufmann87 Nov 17, 2015 7:41 AM in response to mbuck2
    Level 9 (58,746 points)
    Photos for Mac
    Nov 17, 2015 7:41 AM in response to mbuck2

    To get the best performance RAM should be matched, mixing RAM is not recommended but it's your machine. Install the RAM per the direction found in:

     

    http://eshop.macsales.com/installvideos/imac_mid_2010_mem/

     

    Don't over complicate it, installing RAM is extremely simple!!!

  • by mbuck2,

    mbuck2 mbuck2 Nov 17, 2015 10:17 AM in response to rkaufmann87
    Level 1 (0 points)
    Nov 17, 2015 10:17 AM in response to rkaufmann87

    Simple, if you don't have unexpected behaviors and you are replacing the two OEM cards with four identically matched cards within specs. But in many cases, you might be holding a pair of 4GB cards that are higher speeds than the installed pair of 2GB cards, and someone else has moved them around so you don't really know which slots they should all go into. And when the Apple support documentation refer to the 'top' slots as being what everyone else calls the 'bottom' slots, things become anything BUT extremely simple.


    Anyway, I figured it out, and here is what I found.


    1) The way the slots are shown in the video, from left to right they are Bank1 and Bank0. From top to bottom they are DIMM1 and DIMM0. So Bank0/DIMM0 is the bottom right slot, and is the primary one that you should fill if you have only one card.


    IF YOU HAVE MISMATCHED CARDS (different speeds):

    2) This works:

    4GB    4GB  (1600MHz)
    2GB    2GB  (1333MHz)

     

    3) This doesn't:

    2GB    2GB  (1333MHz)

    4GB    4GB  (1600MHz)

     

    4) This works (top and bottom...bottom is how it comes from the factory):

    2GB    2GB  (1333MHz)
    0          0

     

    4) This doesn't (top or bottom)
    0         0

    4GB    4GB  (1600MHz)

     

    5) This seems to work, but your computer will lock up and start chiming.

    4GB    2GB 

    4GB    2GB

     

    So if you have cards with mismatched speeds, do option #1 and you'll get the full benefit of all the cards. The over clocked cards will slow down to match the primary 2GB ones.

     

    Hope this helps someone who doesn't have 4 matched new cards.