Mac Pro 2012 Westmere DualCore RAM upgrade problem

Discussion in 'Mac Pro' started by Fishman17, Aug 15, 2017.

  1. Fishman17 macrumors newbie

    Joined:
    Aug 15, 2017
    Location:
    Halifax
    #1
    Recently upgraded my Mac Pro 2012 (Westmere) with 3x16G of RAM. Hoped I could use the old RAM too and got a quick lesson on DDR2 and DDR3 compatibility. :oops:

    Not satisfied with 48G I bought two more sticks (2x8G), DDR3, same manufacturer, same specs...but when I put them in the system along with my 3x16 the computer gave me the dreaded blinking white memory error light. :eek:

    Try as I might I could find no real difference (besides Gig size) between my original purchase and the new set. Yet no matter how I configure them the system won't start. I tried the 2x8G by themselves, no problem...so it's not the RAM itself. Is there some other hidden spec I should be looking for? o_O

    Purchase 1: OWC 48GB ( 3x16GB ) PC3-10600 DDR3 ECC 1333MHz SDRAM DIMM 240 Pin Memory Upgrade kit
    Purchase 2: OWC 16GB ( 2x8GB ) PC3-10600 DDR3 ECC 1333MHz SDRAM DIMM 240 Pin Memory Upgrade kit
     
  2. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #2
    I don't like OWC ram because of their inherent incompatibility with almost everything else:

    OWC p/n OWC1333D3MPE8GB (8GB modules) and OWC1333D3MPE16G (16GB modules) require that all installed modules be of the same p/n OWC 8GB and/or 16GB modules.

    Other existing Apple or 3rd party 1GB, 2GB and 4GB modules are not supported for use with these kits and need to be removed when these modules are added.

    If I am reading this correctly, it sounds like OWC1333D3MPE8GB and OWC1333D3MPE16G are only designed to only work with identical OWC sticks down to the individual part number level. In other words, you could have added more 8GB OWC RAM of the same part number, but not 16GB, and not ram from anyone else at all, even official Apple RAM.

    I would return the recent purchase and sell your other RAM to get all that OWC out of there, and then just get a new matching set of standard RAM from somewhere else.
     
  3. Fishman17 thread starter macrumors newbie

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    Aug 15, 2017
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    Halifax
    #3
    Actually, we found another set of RAM from another company where they note that if we were to buy 16 it is unable to work with anything but 16s in the other slots. So I think we're just gonna get more OWC 16... play it safe.
     
  4. h9826790 macrumors 604

    h9826790

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    Apr 3, 2014
    Location:
    Hong Kong
    #4
    UDIMM can't mix with RDIMM. Highly likely your 16GB stick is RDIMM and the 8GB stick is UDIMM.
     
  5. Fishman17 thread starter macrumors newbie

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    Aug 15, 2017
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    #5
    Hmmmm..I can't see anything that indicates wether I have one or the other. And nothing on the Mac indicates which kind is installed.
     
  6. h9826790 macrumors 604

    h9826790

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    Hong Kong
    #6
    That's why we don't like OWC. They should clearly state the spec of the RAM, but they didn't.
     
  7. simon lefisch macrumors 6502a

    simon lefisch

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    Sep 29, 2014
    #7
    So where would be the best place to purchase RAM that is compatible with what I have currently installed? Newegg?
     
  8. ActionableMango macrumors 604

    ActionableMango

    Joined:
    Sep 21, 2010
    #8
    Any reputable reseller that shows the full specs is fine. The key is to ensure you get sticks that are compatible with whatever you currently have, either UDIMM (unbuffered) or RDIMM (registered). If you have factory Apple RAM in a Mac Pro 2012, it is UDIMM.
     
  9. simon lefisch macrumors 6502a

    simon lefisch

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    Sep 29, 2014
    #9
    Good to know, thanks! Just purchased a mid-2012 tower so need to learn about the towers (already have a MBP).
     
  10. kschendel macrumors 6502a

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    Dec 9, 2014
    #10
    newegg is fine; datamemorysystems.com and crucial.com are two more sites that have had positive mentions multiple times here on the forums. I've used DMS myself a few times, no complaints.
     
  11. Squuiid macrumors 6502a

    Squuiid

    Joined:
    Oct 31, 2006
    #11
    Even eBay is better than OWC IMO as there are so many direct server pulls of Samsung RDIMMs out there that it's easy to get good quality and cheap used RAM for the cMP.
     
  12. phairphan macrumors 6502a

    phairphan

    Joined:
    Sep 21, 2005
    Location:
    Reject Beach
    #12
    Seconding this. Just make sure it's registered memory, and ideally dual rank (should be noted somewhere as "2R"). Over the years, I believe I recall some folks having trouble with quad ranked DIMMs on the cMP.
     
  13. h9826790 macrumors 604

    h9826790

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    Apr 3, 2014
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    #13
    Yes, 2Rx4 is important especially if you plan to use all 4 slots.
     
  14. carpsafari Suspended

    carpsafari

    Joined:
    Sep 13, 2015
    Location:
    the Netherlands
    #14
    True that, 2 years ago I bought a MP with ram that would not post beyond 1066Mhz, being 1333Mhz and it proved to be 'quad ranked'.
    Good lesson.
     
  15. simon lefisch macrumors 6502a

    simon lefisch

    Joined:
    Sep 29, 2014
    #15
    Wonderful! Thanks for all the info everyone. Will def save me a headache
     

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