2012 Hex with 1333 Ram, Reads as 1066

Discussion in 'Mac Pro' started by TM(tm), Jun 30, 2012.

  1. TM(tm) macrumors newbie

    Joined:
    Jun 22, 2012
    #1
    Title basically says it. I just picked up a 2012 3.33 Hex, installed 32GB(4*8) of G.Skill 1333 non ecc ram. About my Mac reads 32GB of 1066. Is it because my ram is non ecc? Is there anything I can do to make it read my 1333? I tried a PRAM reset.

    Thanks.
     
  2. spacedesign911 macrumors regular

    Joined:
    Jul 22, 2010
    Location:
    Dublin, Ireland
    #2
    Try it one stick and see , then try 2, 3 reboot each time, see if it's across the board, I got a faulty 8gb stick in my 32 from cruicial, and it read as a 4gb and the computer was no faster than my 2006 mac pro 1.1, quad. Replacement ram worked and it's screaming fast now. Huge difference in response.
     
  3. relbbircs macrumors regular

    Joined:
    Nov 26, 2007
    #3
    Your machine is supposed to use ECC ram. Why don't you try using ECC ram and see what happens?

     
  4. Peace macrumors Core

    Peace

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  5. TM(tm) thread starter macrumors newbie

    Joined:
    Jun 22, 2012
    #6
    I reset PRAM. Multiple times.

    I uninstalled my fourth stick of ram, and my system read as 24GB 1333.

    Apparently when installing the fourth stick, it lowers the total speed of the ram to 1066. If all four slots are filled, it read as 1066. Took out the fourth stick, read as 1333 again. Anyone know of a way to remedy this?

    Thanks.
     
  6. Jst0rm macrumors regular

    Joined:
    Feb 25, 2012
  7. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #8
    Unfortunately, there isn't if you want to keep that 4th stick.

    When you add another stick to any particular channel, the interleaving reduces the speed (the has to switch between sticks, and the slowest channel dictates the speed of all other memory channels).

    Hence all sticks run at 1066.

    Now keep in mind, it's far more likely that you'd benefit from the increased capacity rather than the increased memory speed (this is useful for say a cluster). The reason for this tends to be storage, as it's drastically slower than memory (even if the application is completely stored in memory, it still has to wait for data to be written to the disk as well as user input).

    So unless you're trying to solve the fundamental equation of the universe type of usage, you'd almost certainly be better off keeping that additional stick installed (ability to retain more information in memory reduces the need for page outs).
     
  8. chrono1081 macrumors 604

    chrono1081

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    #9
    This! I'm also glad to see a post from you nanofrog. I haven't seen you posts in awhile and they are so informative :)
     
  9. spacedesign911 macrumors regular

    Joined:
    Jul 22, 2010
    Location:
    Dublin, Ireland
    #10
    Just checked mine and can confirm, my 2012 Hex Core 3.3, with 32gb ram, filled with 4x8 gb sticks, 1333 ecc is running at 1333 and not 1066.
    I'd talk to your ram vendor and see what they say, something is not right there, and my speed is a variance with Nanos post.
     
  10. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #11
    If you're running newer LRDIMM's, and I suspect you are given this post, then what you're seeing is possible as the sticks are LRDIMM (= Load Reduced DIMM). This type of DIMM increases capacity and "fools" the memory controller to keep the speed high.

    But traditional memory types (non-ECC and UDIMM specifically as there is no additional chip <register controller>), will see a speed reduction when the controller channels are filled with more than a single DIMM (according to what Intel's published, which is what articles that cover this have used as their source; though many don't mention LRDIMM, as they're newer to the market than when the articles were written).
     
  11. wonderspark macrumors 68030

    wonderspark

    Joined:
    Feb 4, 2010
    Location:
    Oregon
    #12
    I'm another with 4x8GB sticks, all four running at 1333. I bought mine from OWC, and it's ECC.

    Here's an old screenshot:

    [​IMG]
     
  12. Cindori macrumors 68040

    Cindori

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    Jan 17, 2008
    Location:
    Sweden
    #13
    mac pro / Xeons does not require ECC, it simply offers the possibility to use it. mixing ECC with non ECC is not a good idea tho.
     
  13. TM(tm) thread starter macrumors newbie

    Joined:
    Jun 22, 2012
    #14
    Thank you very much for the info nanofrog, and to everyone for your input.

    It looks like I will have to spring for the ECC ram to run 32gb at 1333. But for now I'll be fine with the slower speed. I'm not having to solve the equation for the meaning of the world. ;) yet.
     

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