Can you Mix Different Capacity RAM Sticks?

Discussion in 'Mac Pro' started by simplymuzik3, Aug 9, 2010.

  1. simplymuzik3 macrumors 6502a

    Joined:
    Jan 29, 2009
    #1
    I plan on getting the 8-core w/ the 2GBx4 upgrade from Apple, so that when I want to upgrade, I don't have to "throw away" all my 1GB Sticks. I also plan on ordering 2x4GB sticks and putting them in as well. This would mean 3 sticks/processor (2x@GB and 1x4GB). In the future, I wanted to buy 2 more 4GB sticks, or maybe 8GB sticks. Is it possible to mix/match RAM like this? What are the "rules" when buying RAM?

    I just want to be sure because Im doing a BTO with the 4x2GB sticks from Apple.

    Thanks,
     
  2. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #2
    1Gb, 2GB and 4GB DIMMs should be able to be mixed. You may find some 4GB DIMMs don't work in a mixed environment, check with the manufacturer or where you are buying them from.

    Apple only support unbuffered ECC with the Mac Pros so memory marketed for them will be of this type. 8GB DIMMs are all registered and so while they work (as any registered ECC DDR3 DIMM should) they can't be mixed with unbuffered memory.
     
  3. simplymuzik3 thread starter macrumors 6502a

    Joined:
    Jan 29, 2009
    #3
    Is registered another way of saying "buffered" memory? I was looking around and most only talked about registered/non-registered. So any un-registered/un-buffered memory should be compatible with the RAM from Apple?

    Sorry if that's a stupid question, Im a noob when it comes to memory:eek:
     
  4. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #4
    Yes it is.

    If you just buy Mac Pro compatible memory you should be fine. Just wanted to note that 8GB DIMMs won't work with most Mac Pro certified/supported memory.
     
  5. MacSince1985 macrumors regular

    Joined:
    Oct 18, 2009
    #5
    Here's OWC info regarding the 2009 models. I don't know how much applies to the 2010 line up.

    Does "matched sets" mean "pairs"? or should all the modules match?

    Also left to be seen is whether the 8Gb modules will work, raising RAM capacity to 64GB.
     
  6. Umbongo macrumors 601

    Umbongo

    Joined:
    Sep 14, 2006
    Location:
    England
    #6
    Matched sets should mean the modules are as identical as possible, this gives the best performance and most stability. What the real world out come of that is compared to, say, filling the memory slots with different capacity DIMMs from many different sources hasn't been shown as far as I know.
     

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