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why does increasing the fsb speed, increase the memory bus?

Discussion in 'AMD Overclocking' started by Anon, Sep 6, 2004.

  1. Anon

    Anon Guest

    why does increasing the fsb speed, increase the memory bus?

    can the memory bus be overclocked without overclocking the fsb?

    if so, then does the memory bus have its own clock?
    and why would increasing the fsb clock increase the memory bus?

    if not, (i.i, if you can only increase the mem bus by increasing the
    fsb) then is the memory bus a multiple or a fraction of the speed - or
    either?

    why does fsb set the clock for everything and the memory bus doesn't?

    thanks
     
    Anon, Sep 6, 2004
    #1
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  2. Anon

    rms Guest

    why does increasing the fsb speed, increase the memory bus?

    The clocks for the two busses were tied together in older, simpler
    designs. Only in newer designs has it been possible to have some degree of
    independence between the two.
    Yes, you can do this on most motherboards, like the Abit NF7, but since
    memory designs are generally less tolerant of high busspeeds than cpus,
    generally you run them the same speed or have the memory bus run at some
    fraction of the fsb. There are inefficiencies that crop up when running at
    some fraction other than 1:1, so this is preferred.
    On simpler designs like AthlonXP chipsets, the two are tied together,
    though you can alter the ratio between them. On newer designs like the
    Athlon64, they are completely independent.
    Explained above.
    In the far past it was common to have the memory data bus connected to
    the same pins as the cpu input/output data pins (fsb). Now they are usually
    separate, for increased performance.

    rms
     
    rms, Sep 6, 2004
    #2
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  3. Anon

    Anon Guest

    What's the name of the architecture in the old design(like Athlon XP),
    and the architectural name of the new design(like Athlon 64)?

    What books discuss these things (the old architecture - including its
    name, the new architecture? (bigelow,mueller,minasi?)
    And where are the even more technical things such as the memory
    databus being connected to the same pins, where is that discussed? (do
    I have to look at electronic schematics or is there a watered down
    thing)?

    the most that online resources seem to say is that the athlon 64 has
    no fsb at all.

    I checked the AMD website for information on the AMD Athlon 64
    chipset, but it seems like the chipsets can be made by different
    companies, like Via and SiS. I can't find any standards written by AMD
    discussing the architecture
     
    Anon, Sep 7, 2004
    #3
  4. Anon

    rms Guest

    What books discuss these things (the old architecture - including its
    The Pentium and athlon64 architecture is discussed at length in articles on
    www.arstechnica.com You can search for more yourself.

    rms
     
    rms, Sep 7, 2004
    #4
  5. Anon

    Wes Newell Guest

    There isn't a name afaik. it's just different engineering designs.
    I don't know. I don't need no stinkin book.:)
    Hey, schematics are great if you can read them.
    Only because they they changed the name to HyperTransport. it's basically
    the same thing with a new name, except ram data has it own bus direct to
    the cpu rather than going through the ram bus to the chipset and then from
    there over the FSB to the cpu.
    SIS shows system configurations for all their chipsets that are easy to
    understand. the SIS 748 is for 32bit, and the 755's are for 64 bit. note
    the differences, well there's really just one other than bus name.

    http://www.sis.com/products/
     
    Wes Newell, Sep 7, 2004
    #5
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