MP 1,1-5,1 What RAM to Use to Upgrade 2012 Mac Pro from 32 to 48GB?

Discussion in 'Mac Pro' started by bigusmacus, Aug 3, 2019.

  1. bigusmacus macrumors newbie

    bigusmacus

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    #1
    I have a Mac Pro Mid-2012 6-core 3.46GHz, with 32GB (4x8GB) of OWC memory. I recently bought two 16GB OWC modules thinking I could simply replace two of the 8GB modules with the two 16s. It didn't work. Installing either new module with the 8GB modules wouldn't boot. I returned the memory thinking it must be bad. I bought the modules on Amazon; later I was reading the product page—I had missed a little notice that said you can't use those two 16GB modules with any other modules, only another of the same. The same goes with the already installed 8GB modules—they all have to be the same. To get 48GB using OWC you have to buy three 16GBs. Very disappointing since the four 8GB modules become useless in that case, or I can sell them back to OWC for a fraction of what they cost.

    However, I have another nearly identical Mac Pro that has 32GB (4x8GB) that isn't OWC memory. My question is, if anyone knows, will two Crucial 16GB modules work in conjunction with two of the installed non-OWC 8GB modules? What do other people do to upgrade their Mac Pro from 32GB to 48GB?
     
  2. zipgs macrumors newbie

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    #2
    You need to match your RAM, it needs to be all ECC Registered (PC3-10600R for example) or ECC Unregistered (PC3-10600E) (or just non-ecc, but that's not common in the mac pro) I'm betting that you have ECC Unregistered RAM (ends with E) since that's what most OWC RAM is. Check the crucial, if it ends in R then it should work with the 16GB modules.

    The speed doesn't matter, just the letter on the end (E, R, or U)

    There are no ECC Unregistered 16GB modules that I'm aware of, so if you want to upgrade past 32GB you'll need to replace all of it with ECC Registered.
     
  3. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #3
    Thanks for your reply. This is the OWC that didn't work, but I did see later that you cannot mix OWC modules, different sizes. Something I never knew. Why is that?

    OWC PC8500 DDR3 ECC-R 1066 MHz 240 pin DIMM

    I always assumed that RAM that is ECC Registered could be mixed with other ECC Registered modules of different sizes.

    The Crucial memory is also ECC Registered which is why I am asking if it will work mixed with other ECC Registered modules that are 8GB (excluding the OWC modules). Crucial 32GB Kit (16GBx2) DDR3/DDR3L-1600 MT/s (PC3-12800).
     
  4. zipgs macrumors newbie

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    #4
    It has nothing to do with being OWC RAM, the 16GB are Registered, and the OWC 8GB and smaller are (usually?) unregistered.

    From what I can see, that RAM should work fine.
    --- Post Merged, Aug 3, 2019 ---
    Looking over what they have on their site, I don't believe they even sell Registered 8gb or smaller modules

    https://eshop.macsales.com/shop/memory/owc/apple-mac-pro/2010-2012
     
  5. bigusmacus, Aug 3, 2019
    Last edited: Aug 3, 2019

    bigusmacus thread starter macrumors newbie

    bigusmacus

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    #5
    Thanks, that pretty much clears it up. The smaller modules are for desktops and the larger ECC Registered modules are probably more for servers as most servers use ECC-R memory and desktops usually don't require it.
     
  6. tsialex macrumors 603

    tsialex

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    #6
    It's more complex than that.

    For DDR3 desktop/server memory, simplifying a lot:
    • DDR3 Unbuffered non ECC, this is the common memory used in desktops and usually have 8 memory chips.
    • DDR3 Unbuffered with ECC, this is used in workstations and servers that don't need larger memory sizes, usually have 9 memory chips, or multiple of 9.
    • DDR3 Registered ECC, used in workstations and servers that need lots of RAM, this have 9 memory chips per bank plus a controller chip for the whole DIMM, usually at the centre of the DIMM module.
    This easiest way is to identify what is what is to do a web search with the inscriptions on the chips or the label, but sometimes sellers like OWC remove the label. The spec sheet will show if it's a chip for unbuffered or registered RAM - they are different.

    For unbuffered RAM, if the DIMM have 9 or multiple of 9, it's a ECC DIMM. If it only has 8 or multiple of 8, it's common unbuffered RAM for desktops.
     
  7. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #7
    Ah, my man. I was hoping you would chime in. Thanks for the further clarification.
     
  8. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #8
    Actually, and this is a bit weird, there is OWC 4GB & 8GB ECC-R, but it's not on OWC's site, it's Amazon:

    https://www.amazon.com/gp/product/B01M0HZRLV/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1
     
  9. tsialex macrumors 603

    tsialex

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    #9
  10. bigusmacus, Aug 5, 2019
    Last edited: Aug 5, 2019

    bigusmacus thread starter macrumors newbie

    bigusmacus

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    #10
    Here is a little more info regarding upgrading to 48GB, and this is the answer I've been looking for: "Getting to 48 GB uses three 16 GB DIMMs but getting to 32 GB requires four DIMMs. The last two DIMMs in that combination share a channel, and according to the linked article, registered DIMMs offer a moderate improvement in performance." From an old Apple Forum here. One last question: Does anyone have an opinion or knowledge about this A-Tech RAM? It is the least expensive solution for 48GB using 3 16GB modules.

    And now I found 48GB OWC kit on both OWC and Amazon.
     
  11. tsialex macrumors 603

    tsialex

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    #11
    This is just wrong. You can get 32GB with two 16GB DIMMs but you won’t be using the tri-channel architecture of Nehalem/Westmere Xeons and you will have a little less throughput. 4x8GB again will make you have less throughput since 3rd and 4th DIMMs share the same channel.
     
  12. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #12
    So, using three 16GB would be best, using the first three channels, right?
     
  13. tsialex, Aug 5, 2019
    Last edited: Aug 5, 2019

    tsialex macrumors 603

    tsialex

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    #13
    Yes, 3 x 16GB DIMMs will get you the best possible performance until you have an application that needs more than 48GB.

    After the 48GB tri-channel best performance upgrade, if you app still needs more memory you will be using disk swap, then 4 DIMMs will obviously have better performance than 48GB + disk swap.

    If you need more RAM then 48GB and need the RAM have the best possible throughput, you will need to change your CPU tray to a dual tray, then you can use 6 x 16GB. This will make you have 96GB of RAM with the best possible throughput.
     
  14. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #14
    Ok, one last final clarification, out of curiosity: Will 2-16GB (1&2) and 2-8GB (3&4) even work? All the same ECC R.
     
  15. tsialex macrumors 603

    tsialex

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    #15
    It's possible, but have to be the exactly same type of RAM and depends on rank and bank configuration of the DIMMs to correctly work.
     
  16. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #16
    Thanks, looks like the best solution will be 3 - 16s. I work primarily with large Photoshop files, often 6GB or larger.
     
  17. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #17
    And, another twist. A seller on eBay has the same Mac Pro processor tray that I have, only with 64GB (16x4). The "About This Mac" window shows 64GB. If it recognizes 64GB, is it not using it? How is that possible?

    image.png
     
  18. tsialex macrumors 603

    tsialex

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    #18
    No plot twist, it's just W36xx versus X56xx Xeons. Read the Mac Pro CPU Compatibility List.

    4 DIMMs will always have a performance penalty, only when you need more memory than faster memory you use 4 DIMMs with a single CPU tray, 8 DIMMs with a dual CPU tray.
     
  19. bigusmacus thread starter macrumors newbie

    bigusmacus

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    #19
    Interesting. I have both X5690 and X3690 CPUs (3.46GHz). 3 DIMMs with 48GB should work fine for me, but I may upgrade to a dual processor for one of my Mac Pros. Thanks again for your knowledge! I learn something new every day.
     

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18 August 3, 2019