RAM question

Discussion in 'Mac Pro' started by UncleSchnitty, Feb 7, 2010.

  1. UncleSchnitty macrumors 6502a


    Oct 26, 2007
    I just purchased a refurbished Mac Pro with 2Gbs of ram. I decided to upgrade (with 2X4Gb) has anyone heard of any "bottleneck" issues or anything with going with 10Gbs total?
  2. UncleSchnitty thread starter macrumors 6502a


    Oct 26, 2007
    anything would be helpful, any issues I heard may be rumors I just want to double check
  3. CaptainChunk macrumors 68020


    Apr 16, 2008
    Phoenix, AZ
    Which Mac Pro do you have? I'm assuming the 2008 if it came with 2GB of RAM (presumably the 2x1GB factory modules).

    Generally speaking, the 2008 model performs best with all of its DIMM sockets occupied (which matched pairs in each bank, of course). Take for example, a 16GB configuration. 8x2GB (all 8 sockets populated) would outperform a 4x4GB configuration. Although the 10GB configuration in question isn't on this list, this is a good chart Barefeats published for the 2008 MP:


    Basically, the more sockets occupied, the better.
  4. UncleSchnitty thread starter macrumors 6502a


    Oct 26, 2007
    but 10GB isnt worse then say just the 2X4gb as compared to the 2X1gb and the 2x4gb? I just wana make sure I configure correctly
    Edit: I guess it comes down to the so called "x factor" using all "DR" Ram?
  5. alphaod macrumors Core


    Feb 9, 2008
    Seeing that you bought refurbished with only 2GB of RAM, I will assume it is the not the 2009 Mac Pro… in that case, I would just be sure to follow this guide* and make sure all the sticks are in the right slots.

    *Warning: PDF link.
  6. Genghis Khan macrumors 65816

    Genghis Khan

    Jun 3, 2007
    Melbourne, Australia
    Effectively yes :) That link tells you all you need to know

    But in simple terms for the Harpertown Mac Pro's...
    1) Install RAM in matching pairs
    2) Fill as many slots as you can
    3) Put your biggest RAM sticks in first
    4) Have both risers as close to matching as you can

    This thread (repeats) all you need to know about Harpertown Mac Pro RAM :p
  7. surflordca macrumors 6502a


    Nov 16, 2007
    Ontario, Canada
    I have been running 10gigs of ram for 2 years now with no problems...
  8. Alanbee macrumors newbie

    Dec 4, 2009
    optimal config

    Distilled down...

    The DDR2 Mac Pro's have essentially two different memory "speeds". The machine is optimized to run the memory in a quad channel configuration. So either one or two banks of four identical modules.

    You could install 4 1gb modules and 4 4gb modules, if you so desired, and the memory would be performing at peak efficiency.

    If you have either 2 modules or 6 modules, the memory interface will not be performing at its peak efficiency.

    Having said that, often having the additional memory can be more beneficial than having less memory running more efficiently. It all comes down to what programs you are using and how they allocate the memory.


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