memory speed and performance

Discussion in 'Macintosh Computers' started by gravityplan, Apr 19, 2004.

  1. macrumors newbie

    Mar 26, 2004
    Is 12" pb's bump from 266DDR to 333DDR a big deal? How will this affect performance?
  2. macrumors 68030


    Apr 17, 2004
    The faster you can write to RAM, the faster your programs will be able to start. PC2700 (DDR333) RAM writes and reads at 2.7GBPS PC2100 (DDR266) writes and reads at 2.1GBPS
  3. macrumors 68030

    Capt Underpants

    Jul 23, 2003
    Austin, Texas
    So, unless you need more than 2.1 GB written or read to RAM in a single second, this upgrade isn't important? That kind of sucks. Think about it; the 12" powerbook only holds 1.256 GB of RAM. Am I thinking about this the wrong way, or something?
  4. Moderator emeritus


    Jul 28, 2003
    Citizens Bank Park
    It really doesn't matter how much ram you have in this case. Your ram is written to, read from, and re-writtern all the time. Now anything to and from the ram can be faster. I shouldn't say anything. It can go faster to and from cache. To and from the hard drive is still about the same becasue the hard drive is much slower than ram.
  5. thread starter macrumors newbie

    Mar 26, 2004
    The GB is probably for gigabits, not gigabytes (guessing- I could be wrong). Although either way that sounds really fast.
  6. macrumors 65816


    Oct 6, 2003
    Yes, applications will run a bit faster. How much faster will depend on the particular application. The boost in RAM frequency combined with the boost in bus and cpu frequency will likely produce a noticeable difference when compared to the old model. The memory performance is best understood when mated to the performance of the bus and cpu.

    The new 12" the bus runs at 166, the ram at 333(2xbus), and cpu at about 1333(8xbus). The old 12" bus ran at 133, the ram at 266(2xbus) and cpu at 867(6.5xbus) or 1000(7.5xbus). These numbers are important because you will not get much extra performance as you increase the speed of the cpu unless you increase the bus and ram speed.

    The ratio of bus to cpu frequency is called the bus multiplier (8x in the new 12"PB). Ideally this number should be as low as possible in order to maximize the flow of data through the bus. Applications that use audio and video often are very demanding on the bus and can have problems if too much data tries to pass through this bottleneck.

    The new 12" Powerbook manages a 33% boost to the cpu with only a slight increase to the bus multiplier - an impressive feat. No match for a G5 Powermac with its 2x multiplier but still quite good.

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