what to all the Ram Spec mean?

Discussion in 'MacBook Pro' started by hockeymonkey83, Apr 24, 2007.

  1. hockeymonkey83 macrumors member


    Jan 17, 2007
    Norfolk, VA
    I really havent kept up with the different developments in RAM, but i had a question and was wondering if anybody knew the answer.
    Is there a difference when the RAM is advertised as DDR2 vs DDR2 sdram
    i know the sdram has to do with syncing clock speeds for better performance, but is all DDR2 sdram? Plus aometimes they will say sodimm but that just has to do with the pin set correct?
  2. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    No - SDRAM is a blanket term for most current types of RAM - Synchronous Dynamic Random Access Memory. Synchronous means that reads and writes are tied to a clock pulse on the memory buss. This was introduced with PC66 RAM and is a feature of all computer memory since.

    Flash RAM for example is not synchronous or dynamic.

    So it's like saying 'internal combustion 4 cylinder car motor' and '4 cylinder car motor' DDR2 SDRAM = DDR2

    So in "PC-5300 DDR2-667 memory", DDR2 describes the type of signalling going on, 667 MHz describes the memory speed, and PC-5300 the bandwidth (DDR2-667 is the same as PC2-5300. 5300 = 8 x 667 and is a measure of theoretical bandwidth)

    There is a major difference between PC133, DDR and DDR2 and they are not interchangeable.

    If you hear the term SDRAM on its own, with no "PC" or "DDR" associated with it, then it usually means PC66, PC100 or PC133.

    SODIMM (laptop), DIMM(Desktop) and MicroDIMM (ultraminiature) are different ways of packaging RAM.

    In DDR2 memory, a SODIMM has 200 pins, a DIMM has 240 pins and a MicroDIMM has 172 or 214 pins.

    In DDR2 memory, a SODIMM has 200 pins, a DIMM has 184 pins and a MicroDIMM has 172 pins.

    IN PC66, PC100 and PC133 memory, SODIMMs have 144 pins, DIMMs have 168 pins, and MicroDIMMs have 144 pins

    More terminology and photos here


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