What's the max ram I can add to a late 2009 iMac 27"?

Discussion in 'iMac' started by nyguy4u, Feb 1, 2012.

  1. nyguy4u macrumors member

    Oct 21, 2008
    Hello all..

    I have a late 2009 27" iMac.. 2.8GHz, Quad core i7.

    Right now I have 4GB of RAM that came preloaded onto the computer. 2 GB x 2.

    Excuse the stupid question, but I am not an expert on this, but if I add memory, do I have to stick with 2 GB in each of the 2 empty slots? Or can they be different. Example, 2GB x 2 and 4GB x 2 to equal 12GB total. Or do I need to go with all 4GB x 4?
  2. simsaladimbamba

    Nov 28, 2010
    16 GB RAM is the maximum, you can have two 2 GB sticks and two 4 GB sticks to get 12 GB RAM.
  3. nyguy4u thread starter macrumors member

    Oct 21, 2008
  4. paulrbeers macrumors 68040

    Dec 17, 2009
    2 x 2GB and 2 x 4GB isn't doing it the "wrong way". It is perfectly fine to have two sets of memory of different sizes as long as the memory it is paired with is the same size. See example below.

    Slot 1:2GB
    Slot 2 (paired with 1):2GB
    Slot 3:4GB
    Slot 4 (paired with 3):4GB

    Now doing this, will cause you to lose dual channel memory and thus take a hit in performance:

    Slot 1: 2GB
    Slot 2: 4GB
    Slot 3: 2GB
    Slot 4: 4GB

    While both examples above will get you to 12GB of ram, the second would not be ideal. Both would be stable. I would really recommend you start out with adding 8GB of RAM (see example 1) and if you still think you need to upgrade further due to page outs, then swap out the 2 x 2GB with 2 x 4GB.
  5. nyguy4u thread starter macrumors member

    Oct 21, 2008
    Thank you guys. Appreciate the information.

    I didn't really realize how low memory has come in price. I am almost thinking of just getting (4) 4GB modules.

    I realize the link above isn't the right memory for my Mac.

    Doing some research though.. both crucial and newegg recommend 204 pin. But one recommends PC38500.. and the other recommends PC310600.

    Is there a difference between the two?

    I was looking to get 4 of these..



    I was limiting myself to Kingston.. but I see that iRam has these.. http://www.newegg.com/Product/Product.aspx?Item=N82E16820349034

    I guess these would work, they say PC38500. Just not familiar with iRam.

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