Non-ecc ram in macpros

Discussion in 'Mac Pro' started by ekwipt, Nov 27, 2010.

  1. ekwipt macrumors 6502a

    Jan 14, 2008
    If you put 1600 non-ecc ram in a Mac pro, will it utilize the faster speeds and possible lower timings or will it down clock to regular MacPro ram speed and timings?
  2. Vylen macrumors 65816

    Jun 3, 2010
    Sydney, Australia
    Based on the behaviour of 2010 Mac Pros (and 2009 I guess), it'll clock down.
  3. dissolve macrumors 6502a

    Aug 23, 2009
    It'll definitely down-clock faster RAM as the limitation is with the FSB (I think?). This has no bearing on whether you're using ECC RAM or not. Are you running with a Xeon? I didn't think it would even recognize non-ECC RAM :confused:
  4. nanofrog macrumors G4

    May 6, 2008
    Yes, it will downclock.

    It's not FSB though, as it's a different architecture (FSB was eliminated in favor of an on-die memory controller and the Quick Path Interconnect to communicate to the chipset). But it is due to the max memory controller frequency (spec set by Intel; not all parts can run at 1333MHz either).

    Though on 2009 systems, the firmware is the restriction as Apple fixed it to 1066MHz. So even if the memory controller is actually capable of running 1333MHz (W3570 or W3580 equiped systems for example) and 1333MHz memory is installed, it only runs at 1066MHz (confirmed via testing by MR members). :(

    For older Intel based MP systems, only FB-DIMM's could be used. But this changed with the Nehalem and Westmere based processors.

    The i7 parts using the LGA1366 socket have the same memory controller as the SP Xeons with ECC disabled. So the Xeon variants can run non-ECC memory, but it must all be non-ECC (you cannot mix memory types; same goes for UDIMM and RDIMM - one or the other, never mixed).
  5. ekwipt thread starter macrumors 6502a

    Jan 14, 2008
    I actually have a 2008 MacPro, I was just curious as I read on an audio computer forum of a system builder that pulls out the Apple Ram and uses non-ecc 1600 MHz RAM, I'm guessing he buys the computers from apple with the minimum 4gb RAM and installs the recommended 6gb for 4core machines
  6. dissolve macrumors 6502a

    Aug 23, 2009
    Ah right, no FSB. Is the max memory controller frequency a characteristic of the logic board? Its not a direct limitation of the CPU, correct? Such a shame that Apple would restrict something like that. I guess I shouldn't be surprised though :rolleyes:

    Thanks for clearing this up. I had certainly mixed up information from different places.
  7. nanofrog macrumors G4

    May 6, 2008
    In the case of the 2009's, the limitation is due to the firmware, so that could be considered a board limitation (though this could have been addressed via a firmware update). Assuming 1066 or faster RAM is installed of course. ;)

    For the 2010's, the memory frequency limit is due to the CPU used, assuming the RAM installed is capable of the maximum frequency supported by the CPU (firmware uses standard SPD timings up to the CPU's limit rather than a fixed value).
  8. toxic macrumors 68000

    Nov 9, 2008
    newer MPs can use non-ECC, but not every one will work. I'm not sure what the requirement is, but it has nothing to do with a thermal sensor. I've tried Mushkin Silverline RAM, and my MP didn't even boot, and now I'm using Crucial.

    also, I bought my computer used, and it came with a mix of ECC and non-ECC...worked perfectly fine. I switched it all to non-ECC when I added more RAM, though.
  9. nanofrog macrumors G4

    May 6, 2008
    I'd need to get the details as to what has/hasn't worked, but it's some detail in the specs (i.e. timings are a bit different; gaming memory, such as the Mushkin Silverline is, has a tendency to be hit or miss from what I've seen/heard).

    But standard non-ECC (basic) DDR3 seems to work without incident (standard timings). Crucial for example hasn't had any problems IIRC (list of DDR3 non-ECC).

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