inteliMac- matched 512's or 1.25gb?

Discussion in 'Mac Pro' started by mlrproducts, Jun 29, 2006.

  1. mlrproducts macrumors 6502

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    Apr 18, 2004
    #1
    I have two 512MBs, a 1GB stick, and two 256 sticks. I have to partition them up between an iMac used for photo editing (but not every day), and a Macbook used for general use every day.

    Which would be faster in the iMac, 2x512 matched or 1.25gb?

    Also, would 2x512 be enough for the Macbook with the video ram and whatnot?
     
  2. vv-tim macrumors 6502

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    May 24, 2006
    #2
    Performance-wise, the 2x512mb sticks are going to perform better. If you need a lot of ram for an application and you max out your 1GB, then 1.25GB is going to perform better -in that application-.

    1GB should be enough for most normal use on a Macbook.
     
  3. mlrproducts thread starter macrumors 6502

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    Apr 18, 2004
    #3
    Which would perform better using Aperture on the 17" 1.83ghz iMac?
     
  4. Anonymous Freak macrumors 601

    Anonymous Freak

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    Dec 12, 2002
    Location:
    Cascadia
    #4
    The extra memory. Aperture likes having as much memory as possible; and with the discrete graphics chip, the iMac isn't as dependent on dual-channel memory.

    Also....

    Intel says that the 945 chipset actually is capable of dual-channel mode, even with mismatched memory.

     
  5. vv-tim macrumors 6502

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    May 24, 2006
    #5
    Yep, but if you go deeper into the chipset docs, the asymmetric dual channel isn't the same as symettric dual channel.

    Symmetric dual channel basically is like RAID 0 striping, putting half the data (of a sequential stream) on each stick striping it back and forth. However, Asymmetric dual channel can't do that because of the different sizes. It places the data sequentially on Stick A and then on Stick B. If, for example, data is demanded from both Stick A and B at the same time, a small performance increase is seen because it can pull from both channels at once, but since it's rare, the performance increase is much less than striped symmetric dual channel.
     
  6. mlrproducts thread starter macrumors 6502

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    Apr 18, 2004
    #6
    Ok, so I guess I'll be putting my original idea of 1.25GB in the iMac and the 1GB into the Macbook (at least until I can afford to buy 3GB...)
     
  7. WildCowboy Administrator/Editor

    WildCowboy

    Staff Member

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    Jan 20, 2005
    #7
    You'll probably find the 1.25 GB to be better than the matched 512s...using matched RAM only provides you with a max of about 6% performance improvement over unmatched pairs according to benchmarks. If you're not bumping up against the 1 GB ceiling, the 512s would likely be bit snappier, but OS X likes its RAM a lot, so I think you'll see better performance out of the 1.25 GB setup.
     
  8. Anonymous Freak macrumors 601

    Anonymous Freak

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    #8
    That's true for the iMac and MacBook Pro, but it's debatable for the MacBook and mini. They use chipset-integrated video, which uses main memory for video. This means that the extra memory bandwidth provided by operating in dual-channel mode goes to major use by the video subsystem. Yes, MORE memory is always good; but in this case, the 256 MB difference probably is less important than the extra bandwidth for the video system.
     

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