RAM upgrade options

Discussion in 'Mac Pro' started by sjivan, Aug 24, 2009.

  1. sjivan macrumors member

    Jan 23, 2009
    I have a 2009 Mac Pro (2.66GHz 8-Core) that shipped with 6GB (6X1GB). I'm looking install some more RAM. I believe my computer has 8 memory slots so I'd like to know what memory upgrade options I have.

    Can I add 2 X 2GB, or 1 x 4GB now, with the possibility of adding another 2GB or 4GB stick later. Are these valid combinations?

    I'm looking to upgrade to 10 - 12GB, and would like to do it in a way that my purchase is somewhat future proof so that if I need to go higher and replace some existing 1GB sticks, I can continue using my newly purchased RAM.

    I'd also appreciate any pointers to 3rd party RAM sites.

  2. surflordca macrumors 6502a


    Nov 16, 2007
    Ontario, Canada
    I would buy from OWC. You can go to there site and it will also tell you what your computer can hold...

  3. sjivan thread starter macrumors member

    Jan 23, 2009
    Thanks. I called them and they were very helpful. Here's the info for the benefit of others.

    They suggested that I remove two 1GB sticks and add 4 x 2GB. They said that the sticks work most efficiently in sets of 4's.

    I also asked about the 4GB RAM, and was told that 4GB sticks can only be use with other 4GB sticks and cannot be combined with 1GB or 2GB's. Additionally 4GB sticks can be configured with 3,4, 6 and 8 pieces in the slots.

    I've decided to go with 4x2GB + my existing 1x4GB that adds up to 12GB. The next possible upgrade will be to replace the remaining 4x1GB with 2GB's that will take me up to 16GB. If at some point need to go higher than that, then I'll have to get rid of all my existing RAM and buy new 4GB sticks.
  4. ManiG macrumors member

    Aug 11, 2009
    I believe this is incorrect. The 2009 mac pro's are triple channel, that is it works best with multiples of 3. This is why yours shipped with 6x1g.

    Apparently the performance gain is negligible in triple channel, however.

    If I was in your shoes, I would take the cheapest route to having the ram you need. In other words, keeping your currently installed 6x1g dimms and filling the 2 available slots with 2g modules for a total of 10g.
  5. alphaod macrumors Core


    Feb 9, 2008
    But that would leave the computer with just single channel for all the RAM would it not?
  6. galstaph macrumors 6502a


    Jul 24, 2002
    The Great White North Eh
    IIRC the 6gb (3x1)x2 will run in triple, the 2gb modules in single
  7. ManiG macrumors member

    Aug 11, 2009
  8. sjivan thread starter macrumors member

    Jan 23, 2009
    I specifically asked if I could simply add 2 x 2GB and they said no! and advised me to go with 4x2GB. I would much prefer to have simply added 2x2GB for now and save the extra $100.

    Are you 100% sure that 6x1GB + 2x2GB is a workable configuration? I'm not super concerned about the micro speedups that having it in sets of 3, o4 might bring, as long as 6x1GB + 2x2GB will be not be a total drag.

    Please let me know at the earliest so that I can try to update my order.

  9. ManiG macrumors member

    Aug 11, 2009
    I have not physically confirmed it myself, so I cannot tell you with 100% certainty. Maybe somebody else would chime in.

    However, there is NO REASON, AFAIK, that it shouldn't work. Please ask for the exact reason why 2x2g upgrade would not work. I am curious what their answer would be. I am a little skeptical of them because they already did not demonstrate the knowledge that the new Mac Pros are triple channel and not dual channel.

    Best of luck!
  10. sjivan thread starter macrumors member

    Jan 23, 2009
    I called them and spoke to the tech person. He said they suggested 4x1GB + 4x2GB because I wanted to max out the slots and sets of 4 are more efficient than 6x1GB + 2x2GB, but confirmed that it would work.

    I'm not too worried about the extra microseconds that it might save me so I decided to go with on 2x2GB. They order already shipped but they said that I could return the extra sticks and they would refund me the money.

    Thanks for your advise. 10 vs 12GB is not that important to me right now and when I really need more memory, I'll deal with it. Prices would have hopefully dropped by then.

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