Mac Pro 5.1 1333 memory doubt

Discussion in 'Mac Pro' started by JMVB, May 16, 2016.

  1. JMVB macrumors member


    May 16, 2016
    Hi Guys! I'm not new here, always watch your usefull guides and advices.

    I'm an older Apple user, I've had Macbook's, MBP's, Imac's, hackintosh, and now a Mac pro

    This is my first post

    I have a Mid 2010 mac pro 5.1

    Originally, it have a 2.8ghz quad core Xeon W3530 (Nehalem) and ddr3 1066 RAM

    The thing is, I'd change the processor for a six core 3.2ghz x5679 (Westmere), which according this guide, support 1333 RAM

    I'd upgraded the RAM's to 1333, I'd reset the NVRAM, and nop, still as 1066

    Reading here, says that the X5679 support 1066 memories only...

    I really don't know if it the processor issue or another thong...
  2. ActionableMango macrumors G3


    Sep 21, 2010
    The following Wikipedia article shows the x5679 as supporting 1333 (which conflicts with the Wikipedia article you provided that shows 1066):

    For some reason this processor isn't listed in Intel's ARK, so I cannot get the information from the source.

    I will change the memory speed for this CPU entry in the CPU Compatibility List to "unknown".

    P.S. The mid-2010 comes with 1333 RAM already, so there was no need to upgrade it for speed.
  3. JMVB thread starter macrumors member


    May 16, 2016
    Hi ActionableMango, thanks for reply

    If you take a look to my Mac Pro specs (linked above), you'll realize that my mid 2010 come with 1066

  4. scott.n macrumors 6502

    Dec 17, 2010
    It came with RAM that, because of your original processor, ran at 1066 MHz. The consensus however is that all RAM included in 2010-12 Mac Pros is capable of 1333 MHz when used with a compatible processor.
  5. ActionableMango macrumors G3


    Sep 21, 2010
    On further research, I found this thread where people were arguing about whether this processor is 1066 or 1333:

    This post in the thread indicates that the person got information directly from Intel indicating it is 1066:

    I gets even weirder because this MR user claims it runs at 1333 on his computer (but it isn't a Mac Pro):

    In any case, despite the conflicting information, I've updated the CPU Compatibility List to show "1066" instead of "unknown" for this CPU entry, because that seems to be the best information for how it will work in a Mac Pro.
  6. benjaprud macrumors member

    Apr 9, 2015
    Also some 1333 MHz ram setups will run at 1066 MHz no matter what :

    - Quad-rank memory (very high capacity DIMMs, will even run at 800 MHz if there are 4 of them)
    - Low power 1,35V memory (if there are 4 of them)
  7. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    I think it depends on how many stick you installed. A single quad rank stick may able to run at 1333, but I am not 100% sure a bout that. My old RAM stick can only run at 1333MHz when I install 3 of them, if I use all 4 slots, they will run at 1066MHz only.

    And AFAIK, 1.35V memory just means the RAM stick can support both 1.5V and 1.35V. My current memory is actually 1.35V compatible, and now running at 1333MHz.

    PC3L, 1.35V compatible
    Running at 1333MHz.
    Screen Shot 2016-04-09 at 00.14.07.jpg

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6 May 16, 2016