Using a different Mhz RAM

Discussion in 'iMac' started by Amnesia180, Jun 7, 2017.

  1. Amnesia180 macrumors newbie

    Apr 29, 2017
    Hi all,

    Can you use RAM that is a higher speed than was originally in there.

    Currently, my late 2009 iMac has 4 x 2GB SODIMM DDR3 1066Mhz.

    I'm struggling to find 8gb sticks that aren't 1333Mhz and above. Can I add RAM with a higher Mhz rating if I remove all the RAM already there? (I'm assuming you can't mix and match).
  2. elf69 macrumors 68020


    Jun 2, 2016
    Cornwall UK
    not sure if same but my 2009 unibody macbook (not pro) i had one correct speed and one faster stick.

    worked fine as long as kept the correct slower on in dimm one.
    my 2007 imac this did NOT work the same though so bought correct ram.
    running 1x4 and 1x2 giving 6GB total.
  3. h9826790 macrumors G4


    Apr 3, 2014
    Hong Kong
    Theoretically, you can, and the faster DIMMs will automatically down clock to match the lowest speed DIMM.

    However, in Mac world, that's not necessary the case. Unless someone already perform the exact same upgrade (including identical brand and part number of the DIMMs), you have to try and find out the answer.

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