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Thread: ddr2 clockspeeds and module names explained

  1. #1
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    ddr2 clockspeeds and module names explained

    its getting a little confusing with all those pc5200 and DDR2 675 names, i hope this helps to answer some questions and make some of you that wonder about those numbers understand what they mean


    sdr sends one bit at every clock
    ddr sends one bit at the rising and the falling of each clockcycle wich means it has twice the bandwidth at the same clockspeed (in theory)
    ddr2 uses 2 groups of memory chips wich get a different reference clock, the reference clock for one group of the chips is shifted from the clock signal the other group gets, this means if each memory chip is running at 100mhz the bandwidth of the memory configuration wich the two groups working with a shifted reference clock is twice as high as if all chips would use the same reference clock. since the chips also send a bit at the rising and falling of each clockcycle we get 4 times the bandwidth at the same clockspeed (in theory)

    name of the memory - speed the chips are clocked at - speed the memory modules are clocked at - speed the modules communicate with the chipset at - marketing name based on the claimed theoretical max bandwidth in mb/s

    red = unofficial speed rating wich isnt a set standard by jedec

    sdr 100 = 100mhz internal speed = 100mhz external speed = 100mhz SDR = pc100
    sdr 133 = 133mhz internal speed = 133mhz external speed = 133mhz SDR = pc133
    sdr 150 = 150mhz internal speed = 150mhz external speed = 150mhz SDR = pc150


    ddr 200 = 100mhz internal speed = 100mhz external speed = 200mhz DDR = pc1600
    ddr 266 = 133mhz internal speed = 133mhz external speed = 266mhz DDR = pc2100
    ddr 300 = 150mhz internal speed = 150mhz external speed = 300mhz DDR = pc2400
    ddr 333 = 166mhz internal speed = 166mhz external speed = 333mhz DDR = pc2700
    ddr 375 = 187mhz internal speed = 187mhz external speed = 375mhz DDR = pc3000
    ddr 400 = 200mhz internal speed = 200mhz external speed = 400mhz DDR = pc3200
    ddr 433 = 216mhz internal speed = 216mhz external speed = 433mhz DDR = pc3500
    ddr 466 = 233mhz internal speed = 233mhz external speed = 433mhz DDR = pc3700
    ddr 500 = 250mhz internal speed = 250mhz external speed = 500mhz DDR = pc4000
    ddr 533 = 266mhz internal speed = 266mhz external speed = 533mhz DDR = pc4200
    ddr 566 = 287mhz internal speed = 287mhz external speed = 566mhz DDR = pc4500?
    ddr 600 = 300mhz internal speed = 300mhz external speed = 600mhz DDR = pc4800



    ddr2 400 = 100mhz internal speed = 200mhz external speed = 400mhz DDR = pc2-3200
    ddr2 533 = 133mhz internal speed = 266mhz external speed = 533mhz DDR = pc2-4200
    ddr2 667 = 166mhz internal speed = 333mhz external speed = 667mhz DDR = pc2-5300
    ddr2 800 = 200mhz internal speed = 400mhz external speed = 800mhz DDR = pc2-6400
    ddr2 933 = 233mhz internal speed = 466mhz external speed = 933mhz DDR = pc2-7500
    ddr2 1000 = 250mhz internal speed = 500mhz external speed = 1000mhz DDR = pc2-8000

    ddr2 1066 = 266mhz internal speed = 533mhz external speed = 1066mhz DDR = pc2-8600

    please correct me if im wrong
    Last edited by saaya; 05-15-2005 at 12:54 PM.

  2. #2
    XS_THE_MACHINE [XC] moddolicous's Avatar
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    thanks Saaya, I tihnk this should help out more people upgrading their intel rigs.
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    XS D2OL & RAM News jjcom's Avatar
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    DDR200=PC1600
    DDR266=PC2100
    DDR333=PC2700
    DDR400=PC3200
    DDR433=PC3500
    DDR466=PC3700
    DDR500=PC4000
    DDR533=PC4200
    DDR566=PC4400?
    DDR600=PC4800



    jjcom

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    Here's a rule of thumb for ya Saaya...

    DDR500 = PC4000

    So: take the "DDR" figure & multiply it by 8... or vice versa, take the "PC" figure and divide it by 8

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    nice one saaya

    according to ocz:
    ddr2 at 800Mhz is PC2-6400
    and ddr2 at 1000mhz is PC2-8000

  6. #6
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    thx jesse rabbi and funny_s

    about ddr2 ratings its still confusing me why it got a bump of only 1000 on the rating from 100 to 133 chip clockspeed

    memory chip clockspeed - rating - increase over previous rating

    100 3200
    133 4200 1000
    166 5300 1100
    200 6400 1100
    233 7500? 1100?
    250 8000 500
    266 8600? 1100?

    and is ddr933 an official jedec rating or not? i havent heard about it yet...
    i guess it doesnt exist as intel went from 200fsb to 266fsb?
    but then again pc8600 doesnt run in 1:1 with 266fs as its clocked at 533mhz externally
    Last edited by saaya; 05-13-2005 at 05:01 AM.

  7. #7
    XS News dippyskoodlez's Avatar
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    You have 2 DDR400's in the list, one red, one black. The second one shouldnt be red.
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  8. #8
    XS D2OL & RAM News jjcom's Avatar
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    Quote Originally Posted by saaya
    [COLOR=Red]ddr2 933 = 233mhz internal speed = 466mhz external speed = 800mhz DDR = pc2-7500
    DDR2 933=233mhz internal speed=466mhz external speed=933mhz DDR=PC2-7500

    DDR375=PC3000

    jjcom

  9. #9
    XS News dippyskoodlez's Avatar
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    This how DDRII basicly works?



    Or is it like


    Last edited by dippyskoodlez; 05-13-2005 at 01:33 PM.
    AMD Athlon 64 3700+ @ 300x10________15" Macbook Pro
    2x 512mb Mushkin DDR _______________2x 1Gb DDR2
    Sapphire X850XT____________________X1600M
    DFI Ultra-D_________________________2.16Ghz Merom C2D
    Lian-Li PC7A________________________OS X/XP
    PCP&C 610w Silencer

  10. #10
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    thx for pointing out the typos guys

    dippsy, i dont get what you mean... sorry...
    check lostcircuits, they have a great guide explaining ddr2

  11. #11
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    http://www.lostcircuits.com/memory/ddr3/

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