mac pros memory

Discussion in 'Mac Pro' started by zoran, Dec 5, 2006.

  1. zoran macrumors 68020

    Joined:
    Jun 30, 2005
    #1
    1. Why is it so expensive
    2. Can i buy this kind of memory (mac pros memory) from a pc resseller or only apple?
    3. Is it true that DDR2-SDRAM (PC2-5300) 667MHz ECC fully-buffered DIMM (FB-DIMM) are discontinued?
     
  2. robbieduncan Moderator emeritus

    robbieduncan

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    #2
    Because it's fully buffered. This requires a very expensive hight speed serial controller chip and buffer chips.

    As long has it has sufficient heat sinks then yes you can buy it from an alternative supplier

    No. Apple are not the only people using this, any workstation built around Xeons needs it. This memory will be around for a while yet.
     
  3. CanadaRAM macrumors G5

    CanadaRAM

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    On the Left Coast - Victoria BC Canada
    #3
    #1) Because the RAM module itself has additional circuitry to allow it to run faster and more reliably, because it is error correcting (which requires approx 12% more chips), because it need more attention paid to thermal design, and because overall demand for it is not high enough for large economies of scale to kick in.

    #2) Choose a reputable memory supplier who tests and guarantees Mac compatibility, offers a lifetime warranty, and a no-cost return if it doesn;t work. That way you will be assured of getting the right RAM. MR Readers in the USA often recommend Crucial, OWC and Data Memory Systems.

    #3) Wow, has someone ever been feeding you disinformation. :eek: Take that person or company and strike them from the list of sources you will believe for technical information.
     
  4. Transeau macrumors 6502a

    Transeau

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    #4
    To add to this - FB-DIMMs allow the system to read and write to the memory at the same time. Whereas normal memory can not do that.

    Agreed. Mine came out of a Dell PowerEdge server (Along with my CPU's). I was ordering a server at the same time, and the total price was lower if I bought faster CPU's and More memory in the Dell server. Given, my warranty is going to be a bit more complicated... but I'll manage :)

    This is based on part of Intel's road map and a license agreement between Rambus and Intel. Intel has been in talks with Rambus for using RD-RAM again. But the complexity of the RD-RAM system is a problem. FB-DIMMs truly simplify the memory system. It is possable that Intel will stop using FB-DIMMs in the Xeon chipsets, but not for some time.
     
  5. drbrog macrumors member

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    Apr 29, 2005
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    Chicago
    #5
    Does the Mac Pro memory need to be installed 4 at a time (per riser card) or 2 at a time? I have 512x4 in my MacPro already.
    Thanks
    Jay
     
  6. Cromulent macrumors 603

    Cromulent

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  7. akadmon macrumors 68010

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    #7
    So what exactly is a matched pair? I have 2GB as 2*512KB+2*512KB, so it seems 4 out of the eight slots are used up. Can I add another 2*512KB for a total of 3GB, or do I have to fill all of the remaining slots at the same time? I'm asking because in my mind 3 is a pair and a half, i.e., unmatched :) :confused:
     
  8. Sesshi macrumors G3

    Sesshi

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    #8
    No, matched pairs. ((512 * 2) x 3) are three matched pairs and is therefore OK. At least that's what I'm given to understand. I can try it with three matched pairs later if you like.
     
  9. akadmon macrumors 68010

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    New England
    #9
    Let us know if it works. Thanks.
     
  10. slughead macrumors 68030

    slughead

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    Apr 28, 2004
    #10
    Heat sinks don't matter. The case will cool them regardless, it's just a question of how fast your fans will spin.

    That said, attaching your own (though less extravagant) heat sinks works fine.

    http://www.tenthousandpercent.com/?article=63&section=other

    Also, matched pairs don't matter in the mac pro.

    Just make sure you have an EVEN NUMBER of chips in total, optimally 4 or more.
     
  11. Sesshi macrumors G3

    Sesshi

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    #11
    Sorry I didn't reply earlier - works fine. I was a bit leery of using Precision sticks in there for any extended length of time as the Dell memory slots have a fan directly above it and therefore needs no fancy heatsink.
     
  12. sblasl macrumors 6502a

    sblasl

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    Heber Springs, AR
    #12
    Originally Posted by AppliedVisual

    As for RAM, don't buy 512MB modules! They run at half the bandwidth of the 1 and 2 GB modules! Resale on 512MB FB-DIMMs is practically nothing, so even though it's more espensive, it's best to order with the lowest config that Apple offers using 1GB modules and then add more RAM from another vendor yourself. But I'm hoping that Apple updates their memory prices and choices when they start offering the octo configs.
     
  13. slughead macrumors 68030

    slughead

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    #13
    That makes no sense. How does the size of the chip affect speed? Are there benchmarks verifying this?
     
  14. NATO macrumors 68000

    NATO

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    Northern Ireland
    #14
    It doesn't.. I think he's got confused about the stock 2x512MB that Apple ships the Mac Pro with. It will only run dual-channel because the other riser card is empty.. however if you put another 2x512MB in the lower riser card, the full quad-channel bandwidth will be utilised.
     
  15. damado macrumors 6502

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  16. product26 macrumors 6502a

    product26

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    May 30, 2005
    #16
    the big question is,

    how long should we expect to pay such high prices?
     
  17. CanadaRAM macrumors G5

    CanadaRAM

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    #17
    Ummm... how do you have an even number of modules, unless you install in multiples of 2 (pairs)?

    When you have a PAIR, the two modules that make up that pair must be identical to each other. Thats what's meant by a matched pair.

    If you mean to say -- you do not have to have 4 modules all the same *that is, that the two matched pairs do not have to match each other* then that is correct of course. You can have 2x512 + 2 x 1 Gb.

    IIRC it is because 512 Mb modules have a single rank on the module and the 1 Gb modules have 2 ranks. However I haven't dug up the reference link yet. The other thing is that if you put more than 4 pieces of RAM in the machine, access to modules 5 through 8 will slow the machine down fractionally, as the memory request first goes to the first 2 FBDIMMs on the riser, those FBDIMMs pass the request on to the 3rd and 4th FBDIMMs if they do not have that address. This results in a bit higher latency.

    With FBDIMMs, take every concept you thought you knew about DDR RAM and throw it away. The signalling, organization and performance of FBDIMMs is completely changed. About the only thing that remains, for cost reasons, is the 240 oin packaging.
     
  18. product26 macrumors 6502a

    product26

    Joined:
    May 30, 2005
    #18
    i still think that the best bang for your buck would be to pick up the OEM 2x512 from someone on ebay and install them on the second riser.
     
  19. slughead macrumors 68030

    slughead

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    Apr 28, 2004
    #19
    What I mean to say is, you could have a 512, a 1GB,and a 2GB they would all work without a MATCHED partner. But they do need a partner.

    So you can pair, say, a 1GB with a 2GB.

    My friend has a 1GB and a 512MB and nothing else and they work fine.

    So, as I've said like 3 times already: the mac pro does NOT require a matched pair.

    And, I'll repeat this fact as well: Quad channel doesn't do much in the real world, look it up!
     
  20. product26 macrumors 6502a

    product26

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    May 30, 2005
    #20
    is it possible that all these things are for 64 bit compatibility?
     
  21. zoran thread starter macrumors 68020

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    Jun 30, 2005
    #21
    Are u sure man?
     

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