Mac Pro 2009 single CPU can use the 3x16 GB Ram

Discussion in 'Mac Pro' started by joken, May 18, 2011.

  1. joken macrumors newbie

    joken

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  2. Hellhammer Moderator

    Hellhammer

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    #2
    Don't think so. According to Intel, the maximum RAM is 24GB, though 32GB has been confirmed to work. SP Xeons are based on the non-Xeon CPUs so I doubt they support 16GB modules, which are only available in server world (ECC).
     
  3. Transporteur macrumors 68030

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    #3
    Just because Xeon and desktop processors share the same architecture doesn't mean that the SP versions don't support large memory modules.
    The DP Xeons are the same as the SP ones, just with an additional QPI.

    The chipset, however, might limit the maximum memory size. The DP versions can use up to 192GB with 16GB DIMMS (according to Intels datasheet for the 5520 chipset).
    Unfortunately I couldn't find a memory size for the X58 chipset the SP version uses.
     
  4. joken thread starter macrumors newbie

    joken

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    #4
    Thanks for your reply. :)
    I still wonder, MPs can support 16GB modules.
     
  5. reebzor macrumors 6502a

    reebzor

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    #5
    See what their return policy is like and try it for yourself :D
     
  6. Hellhammer Moderator

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    #6
    I didn't say it does but clearly, there is a difference between SP and DP Xeons. Maybe it is the chipset like you said.

    I found this with Googling, no idea how reliable it is though:

    http://forums.anandtech.com/showthread.php?t=2141994

    However, that doesn't tell are 16GB DIMMs supported since 48GB can be achieved with 6x8GB (and as we know, 8GB DIMMs are supported).
     
  7. Transporteur macrumors 68030

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    #7
    Well, time for someone to test. :D
    Fortunately, 16GB RDIMMs are pretty cheap. :p
     
  8. Umbongo macrumors 601

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    #8
    Intel and board makers don't officially support registered memory on X58 chipsets using 3000 series Xeons; that is why you won't find anywhere officially saying 16GB or 32GB DIMMs work. However registered memory does work. There aren't any technical reasons why 16GB and 32GB DIMMs won't work on single socket Mac Pros. 48GB wasn't supported on the platform until 8GB UDIMMs started coming out.
     
  9. 666sheep macrumors 68040

    666sheep

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    #9
    Could you please post some links where it's described or you did test it yourself? TIA.

    For instance, there was similar situation with last Power Macs: ECC RAM was working OK but ECC Reg wasn't detected.
     
  10. Transporteur macrumors 68030

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    #10
    The 8GB modules Apple ships are RDIMMs, so registered. Registered works with all generations of Mac Pros.
     
  11. Umbongo macrumors 601

    Umbongo

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    #11
    There are plenty of people on here running registered memory on their single processor Mac Pros.

    The 8GB DIMMs sold by Apple, OWC, Transintl and Crucial for Mac Pros are registered DIMMs. A quick search actually turned up an official statement from Apple: http://support.apple.com/kb/HT4584
     
  12. joken thread starter macrumors newbie

    joken

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    #12
    Mac Pro 2009 single CPU can‘t use Registered ECC memory.:confused:
     
  13. 666sheep macrumors 68040

    666sheep

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    #13
    Yeah, but we are talking about 2009 ones ;)

    But thanks, I've missed this info too :)
     
  14. Transporteur macrumors 68030

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    #14
    2009 = 2010. Same machine, same chipset, same memory support (well besides from the different firmware that limits memory speed to 1066MHz on the 2009 machines if you don't update it).
     
  15. Umbongo macrumors 601

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    #15
    They can. I was just showing that Apple actually officially support it on the 2010 Mac Pros, there is no difference between 09 and 10 models in this regard.
     
  16. joken thread starter macrumors newbie

    joken

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    #16
    Only Mac Pro 2009 Dual CPU can use Registered ECC memory.:confused:
     
  17. nanofrog macrumors G4

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    #17
    Those numbers were based on the largest available UDIMM's at the time Nehalem first came out, and they've not updated the actual value (Westmere still states 24GB, even though we know for certain it can run Registered 8GB sticks = 32GB on the SP MP, and 48GB on other SP boards, as they typically run 6x DIMM slots).

    Now as to the 16GB RDIMM's, I'd expect those to work (99.9+% positive). As Umbongo stated, the memory controller is the same as the DP machines (chipset has nothing to do with it any longer). Servers can gobble up memory, and being stuck to 8GB sticks is too limiting. So 16GB sticks is by no means unrealistic, particularly with what the newer processors are designed to do with servers in mind (Intel would have been aware of this from the start, and taken that into consideration when designing the memory controller). 32GB DDR3 sticks may actually show up before DDR3 falls by the wayside.

    If you notice, the 16GB RDIMM's are based on the higher density Samsung memory chips (what allowed them to create an 8GB UDIMM, which IIRC, has been shown to work in the MP by one member, and I know those run on other boards designed for LGA1366 Xeons).

    Registered ECC works on the SP Nehalem and Westmere machines.
     
  18. Umbongo macrumors 601

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    #18
    They've been available for a while now. M393B4G70AM0-CF8 is the 1066MHz part and is officially certified by Intel for Westmere-EP. M393B4G70AM0-CH9 is the 1333MHz part.
     
  19. nanofrog macrumors G4

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    #19
    I recalled seeing an announcement (late March 2011), but didn't think they were actually shipping yet (why I worded it the way I did, as such parts can take some time to reach retail channels). I even half expected a staggered release (16GB first, with 32GB to actually make it to retailers say 6 months later in order to fill OEM orders supply requirements).
     
  20. Transporteur macrumors 68030

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    #20
    So who actually determines the maximum amount of memory now? The CPU (which includes the memory controller these days) or the chipset?

    I was always under the assumption that the chipset has the last word. The numbers Intel states on their data sheets are actually quite confusing. Whereas a Nehalem 5500 or Westmere 5600 CPU states 288GB memory, the 5520 chipset is listed to support 192GB only (12 banks (which Intel states to be the maximum for the 5500 CPUs, so where do the 288GB come from?) at 16GB each).
     
  21. nanofrog macrumors G4

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    #21
    The CPU now, as that's where the memory controller is located. Previously, it was the chipset (FSB based CPU's).

    It is confusing, and I expect the 288GB figure (not sure if this is the hard limit Intel implemented on the memory controller) is based on:
    • 16GB DIMM's * 9 slots * 2 CPU's.
    Assuming the 288GB figure isn't the max value by design, then double the memory due to 32GB RDIMM's (currently the largest sticks out there, and I'm not so sure if they'll go to 64GB RDIMM's before DDR3 is done, as Samsung's already made DDR4 memory in Jan 2011 :eek:).

    Example of an 18 slot board. You might also want to take a look at Supermicro's DP Xeon boards here (notice some are stated with max memory configurations of 192GB and others 288GB)
     

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