MacPro 2008 Ram Options

Discussion in 'Mac Pro' started by nihilisticmonk, Feb 10, 2008.

  1. nihilisticmonk macrumors 6502


    May 4, 2005

    Fate has crossed my path, and has now given me the money to replace my 1st gen MacPro with a brand new one!

    Now, I remember all the drama last year about differing opinions about ram. How to install, how many dimms is optimal etc.

    I wondered what the opinions of the forum are on this matter.
    Apples Manual for the new macpro says 2 dimms is "optimal", but people in the forums say 4 is optimal.

    Also, do you need to cram it full of memory to get any sort of decent performance due to the 8 cores? I remember people talking about the addressable memory of each core making systems really laggy. I have 4gb in my quad, and it's never been a problem.

    So in a nutshell,

    1) What dimm combo should I order from crucial when I place my macpro order
    2)What amount of memory should I use

    3) Is there any evidence of the claims of 2 dimms better than 4 dimms etc. THe manual is useless, and I can't see anywhere near as much info online about the new macpros ram compaired to the old systems.
  2. Analog Kid macrumors 601

    Analog Kid

    Mar 4, 2003
    I'm eager to hear what you find-- just spun up a new Mac Pro myself, but that's for a different thread...

    Since I just got the box today, I'm still running on the stock 2GB. Here's some data I've been keeping in mind as I consider how to fill it up, all from BareFeats:
    Memory tests
    600MHz vs 800MHz
  3. barefeats macrumors 65816


    Jul 6, 2000
    8 of 2GB are best

    I'm not sure what you are doing with your Mac Pro, but for best performance, you'll want 8 FB-DIMMs. And 2GB modules are better than 1GB because they are dual-rank. We've tested all variations using a special 64-bit parallel multi-threaded version of STREAM memory test using a much bigger test sample than normal, so we speak with real world experience.

    We have run the Total Benchmark with After Effects CS3 (8.02). In multiprocessing mode, it maxed all 8 cores and gobbled up 13GB of RAM. When we ran the Retouch Artists benchmark with Photoshop CS3, it gobbled up all 16GB and started making major scratch drive hits. Not all apps gobble up all 16GB but they will all benefit from the speed of having 8 matched dual-rank FB-DIMMs.

    Eight 4GB modules (or 32GB) is just as fast but expensive and may be more than you'll need in capacity.
  4. big dainjerus macrumors regular

    Nov 9, 2007
    How would 4x4GB modules compare? This would leave you with option of picking up more if you ever needed...
  5. nihilisticmonk thread starter macrumors 6502


    May 4, 2005
    Hmm, so, same amount of dimms as cores like the old mac-pro (where 4 dimms was reccomended). In fact, they stated fully populating the banks would actually make it slower due to slowing down reading times or some other stuff.

    So, Matching memory is faster than a mixture. Annoying that you don't get the savings of buying bigger matched kits if you don't want a massive amount of memory.

    BTW, my Mac is used for Photography mostly (Aperture & PS working in Raw).

    I also do video encoding, and play some games :) (Bootcamp).

    I'd still like to hear a definite answer on why fully populated banks is better on the new macpro. is it Dimms matching Cores, etc.
  6. chadosan macrumors newbie

    May 18, 2007
    Key West, Florida
    4x4GB vs 8x2GB

    I'm thinking about getting the 4x4GB leaving the other 4 slots free to populate as the price comes down (maybe in the next 6 months?).

    Am I going to be taking a major speed hit in the interim?
  7. bilbo--baggins macrumors 6502a

    Jan 6, 2006
    I have a comment and a question.

    My comment is that Barefeats don't seem to have read/followed Apple's instructions about adding more memory.

    >>>>>If you add two more sticks, they have to match those first two. You can add two more 1GB sticks in slot 2 on both risers for a total of 4GB. You can NOT add two 2GB sticks to that slot or your system will only report 2GB total.<<<<<

    If you follow Apple's instruction manual, you will move the 1GB module from slot 1 of riser B to slot 2 of riser A, and then add ANY additional matched pair into slots 1 and 2 or riser B. You therefore can add two 2GB sticks and it should recognise 6GB total.

    The only absolute requirement is that each pair must be matched (eg. riser A slot 1 must match slot 2; riser B slot 1 must match slot 2; etc.). My question is that, if 8 matching modules perform better than a mixture - does mixing brands make any difference?

    eg. would the following be any different in performance:

    Riser A
    Slot 1: 1GB Apple
    Slot 2: 1GB Apple
    Slot 3: 1GB Apple
    Slot 4: 1GB Apple

    Riser B
    Slot 1: 1GB Apple
    Slot 2: 1GB Apple
    Slot 3: 1GB Apple
    Slot 4: 1GB Apple


    Riser A
    Slot 1: 1GB Apple
    Slot 2: 1GB Apple
    Slot 3: 1GB Crucial
    Slot 4: 1GB Crucial

    Riser B
    Slot 1: 1GB OWC
    Slot 2: 1GB OWC
    Slot 3: 1GB Misc other brand
    Slot 4: 1GB Misc other brand
  8. nihilisticmonk thread starter macrumors 6502


    May 4, 2005
    I'd love to know the answer to the "fully populated" question as well.

    Why are all banks populated with identical dimms better than just having 2 massive dimms.

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