will the 6-core support more than 16GB?

Discussion in 'Mac Pro' started by the editor, Aug 12, 2010.

  1. the editor macrumors regular

    Joined:
    Apr 21, 2010
    #1
    I was just wondering, will the 6-core 3.33GHz westmere support more than 16GB ?

    only thing is on the Apple site the biggest Memory is 4GB and there are only 4 slots, does 6 or 8 GB memory exist. If we'd put 6GB x4 that would make it 24 GB.

    The 6-core would be a sweet machine if it wasn't for the 4 slots and Max. 16GB ...thats a real deal breaker i guess. in about 2 years time 16GB is like 4GB today....its nothing for a pro machine...mind you that the 6-core only comes with 3GB. :rolleyes:

    i guess Apple really did it this time huh...
     
  2. alust2013 macrumors 601

    alust2013

    Joined:
    Feb 6, 2010
    Location:
    On the fence
    #2
    There are 8GB chips out there, although very expensive. Not sure if apple officially supports them, but they would likely work. I'm not sure where you're getting the increase in need for memory figure though. Not a chance apps will be using 4x the memory as they are now in 2 years.
     
  3. eponym macrumors 6502

    Joined:
    Jul 2, 2010
    #3
    We don't know for sure the exact limitations. You have to wait and see for somebody like OWC to get some test models and see what will work.

    And this is Intel's limitations, not Apple. It has to do with the specific CPU's specs.

    So far, it seems that the 6-core is limited to 24GB. But, it's somewhat implied that this is using 6 slots (6 x 4GB). And since the Pro only has 4 slots, it's possible that it will be limited to 16 GB. We don't know yet if the 8GB DIMMs will work. If they do, then 24GB can be done over 3 slots.
     
  4. strausd macrumors 68030

    Joined:
    Jul 11, 2008
    Location:
    Texas
    #4
    OWC has 8GB RAM modules that worked in 2009 MP. However, the 6 and 12-core MPs support faster RAM. Since nobody has been able to get a hold of a 6 or 12 core machine yet, nobody has been able to test whether or not 1333 MHz 8GB modules will work. But yes, 8GB modules do exist. OWC will test to make sure 8GB 1333 MHz modules will work as soon as they are able to get a new MP.
     
  5. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #5
    This might help clarify this for members. ;)

    According to Intel:
    • SP system max RAM capacity (36xx CPU's; source) = 24GB
    • DP system max RAM capacity (56xx CPU's; source) = 192GB

    The limit of 4x DIMM slots per CPU (8 total) on the DP systems = 8 * 16GB = 128GB max. If it's less than that, then it's an artificial limit set in the firmware.

    It's the SP systems that aren't so pretty. The 24GB limit from Intel is based on 6x DIMM slots (max 2x DIMM's per channel @ 3 channels = 6), so the math means they're limited to 4GB DIMM's max. As there's only 4x DIMM slots, the capacity limit is only 16GB in the SP MP's, and where that capacity number is originating from. :(

    SP system owners won't be able to get around this IMO, unless Intel actually allows the firmware to be written in a manner that will actually allow 8GB sticks to be used in triple channel mode (the shared DIMM slot left empty). But this is doubtful, as it's easier to limit the DIMM capacity so all slots can be filled (idiot proofing).

    This may cause some users to be forced to go with a DP system if they must have more RAM than 16GB. Sucks, as the SP Hex core otherwise is a nice balance of performance and cost IMO.

    BTW, DDR3 is actually available in 16GB DIMM's (1066MHz, RDIMM, CL = 7; example). Just a mere $1400 per DIMM. :eek: :p

    The timings are a bit different.

    JEDEC DDR3 timings:
    7-7-7-20 for DDR3-1066
    7-7-7-24 for DDR3-1333
     

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