Late 2015 iMac: New ram of same specs, not playing nice with old

Discussion in 'iMac' started by maves, Sep 30, 2018.

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  1. maves macrumors newbie

    maves

    Joined:
    Sep 30, 2018
    #1
    Hello,

    I recently bought 2x8gb @1867ghz sticks of RAM to add to the 16gb (also 2x8gb @1867ghz) that is in my late 2015 iMac.

    Despite tracking down RAM that is the same brand, clock speed, and latency; when installed together, the system shows the speed as 1333ghz.

    I've attached a picture of the old and new RAM. Is there something I'm missing? Is there any reason these sticks should not be completely compatible?

    [​IMG][/url][/IMG]
    https://imgur.com/dhgDVM1

    Thanks
     
  2. droog Suspended

    droog

    Joined:
    Apr 10, 2018
    #2
    Try using the new ram independently of the original ram. If it boots to 1867, then their is a good chance the imac down clocks while running quad channel. If this is so, you'd need 2x16 to reach 1876. You'll probably be fine at 1333 unless you are doing a bunch of gaming.
     
  3. robbier macrumors member

    Joined:
    Apr 27, 2008
    #3
    I would also try a PRAM reset and then see if the RAM is running at the proper speed.
     
  4. nambuccaheadsau macrumors 68000

    nambuccaheadsau

    Joined:
    Oct 19, 2007
    Location:
    Nambucca Heads Australia
    #4
    Where did you get the modules? OWC and Crucial for me.
     

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3 September 30, 2018