SDRAM upgrade for mid 2011 27" iMac

Discussion in 'iMac' started by macnicol, Oct 25, 2018.

  1. macnicol macrumors newbie


    Mar 1, 2006
    My late 2009 27in iMac that just "died", probably the power supply, it has 16gb of 1066MHz DDR3 SDRAM. I'm looking at replacing it with a mid 2011 27in iMac which has 4GB 1333MHz DDR3 SDRAM. Can I use the 1066MHz DDR3 SDRAM in place of the 1333MHz DDR3 SDRAM? I realize this would probably be a downgrade in overall system speed, but will it work?
  2. keysofanxiety macrumors G3


    Nov 23, 2011
    Not sure why the user above said nope. You definitely can use slower RAM in a machine which has faster stock RAM. It'll just run at the slower speed (1066MHz vs 1333MHz).
  3. EugW macrumors 603


    Jun 18, 2017
    I believe that may be true for the 2011 iMac.

    However, that is not true for all Macs. Some Macs will just refuse to boot.
  4. mikehalloran macrumors 65816

    Oct 14, 2018
    The Sillie Con Valley
    As far as I know, the minimum requirement for a 2011 is 1333 MHz PC3-10600 DDR3 SDRAM.

    RAM from a 2009 is 1066MHz DDR3 PC3-8500

    That has been my experience with the 2011. YMMV
  5. EugW macrumors 603


    Jun 18, 2017
  6. DeltaMac macrumors G3


    Jul 30, 2003
    If you have the RAM now, you can certainly try it.
    If it boots, and seems to work normally --- and also passes the Diagnostics test, then great. The memory bus will operate at the speed of the slowest RAM installed, but if it works, use it.
    (It's entirely possible that a failing power supply can damage installed RAM sticks - I've seen it happen before, so don't go in with the expectation that RAM that you might pull out of a dead iMac is good... That remains to be seen (and tested!)

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6 October 25, 2018