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DDR Memory help

  1. Dec 4, 2012 #1
    I know if I have a DDR2 Memory that is 800 MHz and it is 64 Bit the math to findout the Data Transfer is

    800,000,000 X 64 = Data Transfer.
    But will this give me the Data Transfer in just Bits Per SEC. or MB Per SEC?
  2. jcsd
  3. Dec 4, 2012 #2


    Staff: Mentor

    Last edited: Dec 4, 2012
  4. Dec 4, 2012 #3
    I did have a look at your link and I think this got me more confused.

    If I want to know my Transfer Rate for my DDR2 800MHz 64 Bit DiMM in Bytes I do the math like this

    800MHz X 64 then take the out come and Divid by 8

    Will give me Transfer in Bytes per sec Right?
  5. Dec 4, 2012 #4


    Staff: Mentor

    Yes, that seems right. I gave you the link because it had several tables where the Hz was listed along with the MB/sec to give you a comparison and perhaps help answer other related questions.

    I noticed that a given Hz was doubled because the memory is read on the up cycle and on the down cycle of the clock signal. If the memory is transferred in parallel on a 64 bit or larger bus then your answer 800 * 8 is the MB/sec speed is correct but if say the data was transferred on a smaller 32 bit bus then the rate would be half or 800 * 8 / 2 MB/sec.
    Last edited: Dec 5, 2012
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