Memory Confusion on new iMac

Discussion in 'iMac' started by hakr100, Feb 17, 2014.

  1. hakr100 macrumors 6502a

    Mar 1, 2011
    East Coast
    Got my new iMac last week with 8GB of ram, ordered another 8GB of Crucial from Amazon.

    Memory arrived today. One strip of ram chips, 8GB. I thought ram had to be inserted in the iMac in pairs.

    Inserted strip of ram, machine booted right up properly and reported everything A'OK, per attached screen shot.

    So, memory does not have to be inserted in matched pairs? I am confused. :confused:

    Attached Files:

  2. DeltaMac macrumors G3


    Jul 30, 2003
    If you meant to order a pair of 4 GB chips, then you should have returned that single 8 GB for the pair that you really wanted.

    But, no, most Macs don't require the RAM to be matched pairs.
    You WILL measure somewhat better performance with a matched pair, but you would not likely notice any difference in real use.

    And, now you know that each slot supports up to 8 GB, so you could add a second 8 GB chip to the open slot.
  3. hakr100 thread starter macrumors 6502a

    Mar 1, 2011
    East Coast
    No, I just ordered the 8GB and got the one stick. I figured it would show up as two sticks. But it seems to work fine. Well, another day, another lesson learned!
  4. Chippy99 macrumors 6502a

    Apr 28, 2012
    One stick will work but will only work at half the speed. The CPU has a dual channel memory controller, so with only 1 stick loaded, it can only drive one channel and operates at half the possible speed. That's why you need to install it in pairs.
  5. T'hain Esh Kelch macrumors 601

    T'hain Esh Kelch

    Aug 5, 2001
    The old Mac Pro was required to have memory installed in pairs, and I assume the new one also requires it. I believe it is the only machine that has had that dependency.

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