16gb RAM kit purchased (2 x 8gb) - need guidance

Discussion in 'Mac Pro' started by leftPCbehind209, Oct 8, 2010.

  1. leftPCbehind209 macrumors member

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    Aug 23, 2010
    #1
    I purchased the 16gb (2 x 8gb) kit from OWC for my Hex core.

    Previously, I read threads that discussed you may get better performance if installed in sets of threes (3 x 8gb)....but I also read that the real world difference would be minimal.

    Fast forward to now...I believe I read where someone said that if someone has 2 x 8gb sticks, and they try to add a third 8gb in the future that it "might not match".

    What does that mean? My plan was to buy another 8gb stick in about 9-12 months. Do I need to buy it now to make sure it "matches"? Also, as I understand, the 2 sticks need to go in the 1st and 2nd slot, right?
     
  2. Hellhammer Moderator

    Hellhammer

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    Finland
    #2
    At least OWC states that their 8GB modules cannot be mixed with other brands thus you have to buy the exactly same RAM from the same manufacturer, otherwise it may not work. What this means is that you can't buy from OWC now and then buy the 3rd stick from Crucial.

    As long as you buy them from the same manufacturer and the specs match, it should work. You should ask from the seller/manufacturer though, just to confirm.
     
  3. leftPCbehind209 thread starter macrumors member

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    Aug 23, 2010
    #3
    Okay, thanks.

    When installing the 2 sticks I've purchased, do I replace the two sticks at the edge with new ones?
     
  4. Hellhammer Moderator

    Hellhammer

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    #4
    It shouldn't matter but yes, replace the original RAM, just to be sure. You can't use it along with the 8GB modules IIRC so it's safe to remove them
     
  5. ljonesj macrumors 6502a

    ljonesj

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    Kingsport TN
    #5
    thats a bunch of bull from owc as long as its the same latency and clock speed it should not matter owc just wants to get your money
     
  6. Hellhammer Moderator

    Hellhammer

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    #6
    Do you have anything to prove that or are you just making up your own facts? I hope that it's just OWC crap but would like to see some proofs before I will believe
     
  7. leftPCbehind209 thread starter macrumors member

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    Aug 23, 2010
    #7
    Just to clear things up, it wasn't OWC that told me that...I read it in a thread on this board that I can't seem to find now.
     
  8. Mac_Max macrumors 6502

    Joined:
    Mar 8, 2004
    #8
    The Core i7/Xeon memory controller is amazingly flexible. The whole "don't mix memory" bit is just a holdover from when Apple released a firmware update for most Macs in 2002ish that killed a lot of crappy 3rd party memory. Good, up to spec, memory wasn't an issue. Also back in the EDO/FPM days in the 90s, mixing memory of different densities could cause occasional issues so low density memory was always the recommendation.

    These days however, most memory comes in one of three densities (and they're all "low" density) and JDEC doesn't allow a lot of the funny business from years past since DRAM has gotten so cheap (there's no excuse for packing 32 chips on a DIMM/Memory capacity meant for 8 chips).

    In your case, don't sweat the triple channel for now. Do it when budget allows. If you really need that much RAM, I'm assuming you're doing something like 3D work or video editing that eats up a ton of RAM and you'll notice a large speedup from that by itself.
     
  9. malch macrumors 6502

    Joined:
    Jan 20, 2008
    #9
    When I asked OWC about adding RAM in the future (I was worried about compatibility, like the OP), a salesperson wrote back to say:
    "If for some reason we were to update these chips later on I can assure you we would manufacture them to be backwards compatible.
    But I wouldn't worry, we still sell memory for machines that can only support 32MB of RAM =)"

    Like the OP I'm not able to afford 3 8GB sticks now, so I've been debating whether to buy just two now (and add a third stick when I can afford it), or whether to purchase three 4GB sticks instead.
    I've been worried about having just two 8GB sticks because, like the OP, I've read on these threads about the Mac Pro liking three slots filled, not two.
    But people seem to be saying that it might not make that much of a real-world difference, so I'm thinking I might follow the OP's lead.
    Anyway, I thought I'd add the info from the salesperson at OWC.
    regards,
    malch
     

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