MacBook Pro Memory

Discussion in 'MacBook Pro' started by Madhorsey, Jun 14, 2011.

  1. Madhorsey macrumors newbie

    Jun 14, 2011
    Hi Guys and Gals

    I need some advices here. I've got MacBook Pro 6,2 (mid 2010) 15" 2.66 Core i7. It came with 4 GB RAM which I believe ran at 1333 MHz.

    I recently bought an aftermarket 8 GB upgrade. A buddy of mine bought this for me from Frys in the States. I live in South Africa. Sadly, one of the DIMM is faulty. Thus my Macbook is now running at 6GB but only at 1066 MHz. The packaging and the sticker on the DIMM says 1333 MHz. Is this some sort of Apple magic playing here? BTW, the DIMMs are made by Patriot Memory.

    So, I my question is as follow: Do you guys recommend 4 GB at 1333 or 6 GB at 1066?

    I appreciate your inputs..
  2. Apple Expert macrumors 65816

    Jan 31, 2010
    Always match the sets. 2gb x 2gb or 4gb x 4gb. This is what is recommended.
  3. Orlandoech macrumors 68040


    Jun 2, 2011
    Salt Lake City, UT
    2010 MBP only ran at 1066 and Id recommend 6GB over 4GB memory regardless.

    It shows 6GB at 1066 because it scaled it down to 1066 because thats all the bus can do.
  4. Madhorsey thread starter macrumors newbie

    Jun 14, 2011

    Thanks for this. My dilemma is that I have to run @#$%@#$ Windows on VM which requires at least 4GB... :(

    But I will consider your recommendation. Thanks
  5. Madhorsey thread starter macrumors newbie

    Jun 14, 2011
    I thought it might be the hardware limitations. Thanks for clarifying..
  6. Madhorsey thread starter macrumors newbie

    Jun 14, 2011
    Just curious, any particular reasons why?
  7. Kyzelios macrumors 6502

    Mar 6, 2011
    It is recommended to use memory in matched pairs because it will run in what is known as a "dual channel" configuration, providing better memory performance.
  8. drambuie macrumors 6502a

    Feb 16, 2010
    When running a dual channel memory system in single channel mode, the memory bandwidth will be reduced by about 8 - 10%. That decrease would be hardly noticeable in normal computer use. In your case where you have a 4GB DIMM and a 2GB DIMM, the first 4GB will run in dual channel mode, and the upper 2GB will run in single channel mode, so the odds are that you will be running in dual channel mode in the lower 4GB most of the time.

    It is more important that the timings are matched on both modules. The system will run at the slowest timing. The Cl timing for 1066MHz RAM is usually 7, and the Cl timing for 1333MHz is usually slower at 9. However, when 1333MHz RAM is run at 1066MHz, the Cl timing should change to 7. This is due to timing vs clock frequency tables built into the RAM chips.
  9. Madhorsey thread starter macrumors newbie

    Jun 14, 2011
    Thank you for this comprehensive explanation. I am with a company that requires me to run the VM for Windows Apps. This is till end of July. So, I'll stick with 6Gb till I am no longer required to run the VM. It's a pity that the other DIMM is faulty.. :(
  10. alust2013 macrumors 601


    Feb 6, 2010
    On the fence
    It happens sometimes, but 6GB is definitely the better option here, as VMs are memory hungry beasts, even if it doesn't have quite the bandwidth that the dual channel 4GB does.

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