Can you combine two 4GB memory with two 8GB?

Discussion in 'Mac Pro' started by td2243, Jan 4, 2014.

  1. td2243 macrumors 6502

    Mar 14, 2013
    Santa Fe, NM
    I'm curious how the RAM can be combined? Does it all have to be the same, or can there be pairs that match, etc? I'm thinking of getting the 12GB model, taking out one of the 4GB strips and replace the two empty slots with two 16s or 8s.

    Do brands have to be the same as well?
  2. CH12671 macrumors 6502

    Dec 29, 2013
    Southern US


    A quick search would find it....I asked the exact same question in this forum. The answer is you should be able to. There may be an issue with the arrangement, and the chipset may want you to arrange them as 8+4, and 8+4 rather than 8+8 and 4+4. But the machine will let you know quickly if it doesn't like something.

    What you CANNOT do, though, is mix 16 gig chips in there as they are registered (RDIMM) and the 4's and 8's are unbuffered (UDIMM) chips.
    As long as you stay away from that combination you 'should' be fine.

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