Bought ECC ram but mac pro says it is not

Discussion in 'Mac Pro' started by andyUKr, Dec 10, 2010.

  1. andyUKr macrumors member

    Joined:
    Mar 17, 2010
    #1
    Hi All

    I just bought samsum 4gb ram stick for my 2010 mac pro. the website from which i bought it said it was ECC. I installed it and when i go to about this mac, it tells me that this RAM is not ECC. I kept the 3gb of the original ram in the machine.

    So i am a bit puzzled how it is possible that my apparently now non ecc ram works with the original ecc ram. I did not think it was possible.

    Or am i damaging my mac by mixing two types of memories?
     
  2. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #2
    Can you provide the model number of the memory?

    I ask, as the website could have been wrong, or they even sent the wrong item. It's a place to start anyway. ;)
     
  3. andyUKr thread starter macrumors member

    Joined:
    Mar 17, 2010
    #3
    M378b5272ch0. Ch9
     
  4. toxic macrumors 68000

    Joined:
    Nov 9, 2008
    #4
    ECC RAM and non-ECC will work together. no idea if it does anything bad, by my (used) MP came like that. now I just use non-ECC, though.
     
  5. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #5
    Are you sure that is the model? Doesn't seem right. You can look up all the details on Samsung's site.
     
  6. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #6
    This isn't a model/part number (checked Samsung, and got nothing).

    What we're looking for will be on the sticker pasted on the DIMM, not the brand of chip that was used on the PCB itself. Memory vendors will have their offerings made by an ODM who will order whatever chip that will meet the given spec for the lowest cost (in actuality, they usually already have a standard line that vendors can chose from, then slap the sticker on bearing their own Part and Serial numbers).

    This seems odd to me, as there's no indication in the Data Sheet that the memory controller will allow this (Nehalem or Westmere based Xeons), and even if it were (what's been possible in the past), is that you'd need access to the system firmware in order to Disable Parity Checking for it to work.

    :confused: :confused:
     
  7. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #7
    ECC memory has always worked like this I thought, the currently Xeon platform isn't the only one where mixing DIMMs has just disabled the ECC functionality.
     
  8. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #8
    It's been possible in some cases to mix non-ECC with Unbuffered ECC (it all just runs as non-ECC; remember, they're the same, but with ECC support added to Unbuffered - why it's even possible to work), but you typically had to be able to access the firmware to disable the Parity Check for the memory (this is changing).

    RDIMM is a different story, due to the Register chip on the PCB (will not mix with Unbuffered or non-ECC). But I'm still used to having to check a system's firmware when I know such a memory mixture will be used (rare, but does happen, such as when the system needs more RAM, and Unbuffered is no longer available).

    Now it may be possible that the 2009/10 MP's firmware is automatically disabling the Parity Check when combining Unbuffered and non-ECC (some other boards do this), but it's not stated anywhere I've seen (yes or no). But the aspect of Registered ECC combined with other types still holds true (won't work).

    When I checked Intel's datasheet on these processors, they don't show the ability to mix the different memory types at all (does not show any mix of non-ECC, Unbuffered, or Registered with any other type other than itself; all configurations show the same type used).

    This doesn't mean non-ECC won't mix with Unbuffered necessarily, but that they didn't want it mentioned anywhere, even in official documentation (just like they don't mention that the ICH10/R still have a PCI interface - they want to get designers/board makers to shift away from whatever's no longer mentioned, as they've planned to EOL it in the near future or no longer wish to support it).

    Hope this isn't too confusing.
     
  9. andyUKr thread starter macrumors member

    Joined:
    Mar 17, 2010
    #9
    Thnx all for your replies and all the explanations.

    Ram turned out to be non ecc as was confirmed to me by samsung

    The shop took it back, refunded me and apologised which was nice

    But i had this non ecc ram mixed with the ecc ram in my mac pro for 1 day and it all worked fine. At least on the surface.
     

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