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Underclock AMD X2 4800/2500?

Discussion in 'AMD Overclocking' started by wdoe999@yahoo.com, Feb 6, 2008.

  1. Guest

    Hi - I've done a lot of digging and can't find the answer to this...

    I have an AMD X2 65nm 4800 which runs at 2500MHz.
    I also have DDR2-6400 800MHz RAM.

    Would the system be faster if I used the stock 12.5 multiplier while
    the RAM runs at 714MHz, or is it better to drop the multiplier to 12
    and let the RAM run at a full 800MHz?

    I've found tests which show that the 4600 (2400MHz) outperforms the
    4800. The articles don't explicitly say it, but I gather it is due to
    the multiplier. I'm assuming that simply dropping the multiplier
    would make th 4800 run as well as the 4600? Is it is simple as that,
    or is there something I'm missing.

    Anyway, my apologies for posting an "underclocking" question. I don't
    like to live dangerously.

    Thanks.
    , Feb 6, 2008
    #1
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  2. Wes Newell Guest

    On Tue, 05 Feb 2008 16:54:50 -0800, wdoe999 wrote:

    > Hi - I've done a lot of digging and can't find the answer to this...
    >
    > I have an AMD X2 65nm 4800 which runs at 2500MHz. I also have DDR2-6400
    > 800MHz RAM.
    >
    > Would the system be faster if I used the stock 12.5 multiplier while the
    > RAM runs at 714MHz, or is it better to drop the multiplier to 12 and let
    > the RAM run at a full 800MHz?
    >

    The multiplier has no effect on the ram speed. The system bus does. The
    normal system bus is 200MHz. And normal ram bus speed for for PC6400 DDR2
    ram is 200MHz also. 800MHz is not a real bus speed. It's really a data
    rate with DDR2 having a 4:1 data rate. Older DDR PC3200 also has a ram
    bus speed of 200MHz, but it only has a data rate of 2:1. Some MB bioses
    use the real ram bus speed while others may use the bogus speeds for
    settings. Look at your dram settings to determine this.

    > I've found tests which show that the 4600 (2400MHz) outperforms the
    > 4800. The articles don't explicitly say it, but I gather it is due to
    > the multiplier. I'm assuming that simply dropping the multiplier would
    > make th 4800 run as well as the 4600? Is it is simple as that, or is
    > there something I'm missing.
    >

    I think you've misinterpreted something. An AM2 x2 4800+ will be faster
    than an AM2 X2 4600+. Perhaps you're looking at 939 v. AM2 platforms or
    possibly CPU's with different L2 cache sizes or different cores.

    > Anyway, my apologies for posting an "underclocking" question. I don't
    > like to live dangerously.
    >

    That being the case, I'd suggest you leave well enough alone. If you just
    have to have more speed. The basics are to lower the HT speed. Lower the
    base ram speed. And then increase the system bus speed to increase the
    cpu speed. All of my system have X2 3800's in them. I can increase the
    system bus from 200 to 233 MHz without any problems thus bringing the cpu
    speed up from 2000MHz (10x200) to 2330MHz (10x233), and with monor
    adjustments could get them a lot faster. But why? The stock 2000Mhz is
    plenty fast enough for my use. In fact I run cpufreq and normally the cpu
    speed stays at 1000MHz, only going higher when I stress it. To get max
    speed out of a system you'll find yourself screwing with voltages, better
    cpu coolers, etc. If you don't know what your doing or have to time learn
    by trial and error, forget it. In the end, it won't help that much.




    --
    Want the ultimate in free OTA SD/HDTV Recorder? http://mythtv.org
    My Tivo Experience http://wesnewell.no-ip.com/tivo.htm
    Tivo HD/S3 compared http://wesnewell.no-ip.com/mythtivo.htm
    AMD cpu help http://wesnewell.no-ip.com/cpu.php
    Wes Newell, Feb 6, 2008
    #2
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  3. Guest

    On Feb 7, 12:41 am, Wes Newell <> wrote:
    > On Tue, 05 Feb 2008 16:54:50 -0800, wdoe999 wrote:
    > > Hi - I've done a lot of digging and can't find the answer to this...

    >
    > > I have an AMD X2 65nm 4800 which runs at 2500MHz. I also have DDR2-6400
    > > 800MHz RAM.

    >
    > > Would the system be faster if I used the stock 12.5 multiplier while the
    > > RAM runs at 714MHz, or is it better to drop the multiplier to 12 and let
    > > the RAM run at a full 800MHz?

    >
    > The multiplier has no effect on the ram speed. The system bus does. The
    > normal system bus is 200MHz. And normal ram bus speed for for PC6400 DDR2
    > ram is 200MHz also. 800MHz is not a real bus speed. It's really a data
    > rate with DDR2 having a 4:1 data rate. Older DDR PC3200 also has a ram
    > bus speed of 200MHz, but it only has a data rate of 2:1. Some MB bioses
    > use the real ram bus speed while others may use the bogus speeds for
    > settings. Look at your dram settings to determine this.
    >
    > > I've found tests which show that the 4600 (2400MHz) outperforms the
    > > 4800.  The articles don't explicitly say it, but I gather it is due to
    > > the multiplier.  I'm assuming that simply dropping the multiplier would
    > > make th 4800 run as well as the 4600?  Is it is simple as that, or is
    > > there something I'm missing.

    >
    > I think you've misinterpreted something. An AM2 x2 4800+ will be faster
    > than an AM2 X2 4600+. Perhaps you're looking at 939 v. AM2 platforms or
    > possibly CPU's with different L2 cache sizes or different cores.
    >
    > > Anyway, my apologies for posting an "underclocking" question.  I don't
    > > like to live dangerously.

    >
    > That being the case, I'd suggest you leave well enough alone. If you just
    > have to have more speed. The basics are to lower the HT speed. Lower the
    > base ram speed. And then increase the system bus speed to increase the
    > cpu speed. All of my system have X2 3800's in them. I can increase the
    > system bus from 200 to 233 MHz without any problems thus bringing the cpu
    > speed up from 2000MHz (10x200) to 2330MHz (10x233), and with monor
    > adjustments could get them a lot faster. But why? The stock 2000Mhz is
    > plenty fast enough for my use. In fact I run cpufreq and normally the cpu
    > speed stays at 1000MHz, only going higher when I stress it. To get max
    > speed out of a system you'll find yourself screwing with voltages, better
    > cpu coolers, etc. If you don't know what your doing or have to time learn
    > by trial and error, forget it. In the end, it won't help that much.
    >
    > --
    > Want the ultimate in free OTA SD/HDTV Recorder?http://mythtv.org
    > My Tivo Experiencehttp://wesnewell.no-ip.com/tivo.htm
    > Tivo HD/S3 comparedhttp://wesnewell.no-ip.com/mythtivo.htm
    > AMD cpu helphttp://wesnewell.no-ip.com/cpu.php


    Your overall system will be faster if left at stock speeds rather
    dropping the CPU down to 12x just to get the RAM speed up. The RAM
    speed does not greatly affect the overall speed of the machine. Or
    you could drop down to 12x and increase the FSB to 208 to get you CPU
    back to stock speed if you don't want to overclock the CPU but your
    RAM would be at 832MHz. With your CPU at 2500, a comparison between
    714 and 832 for your RAM in a benchmark would show almost no
    difference in RAM bandwidth with no other changes to RAM settings.
    About all that would happen is your latencies would drop very slightly
    with the faster RAM clock. Most BIOS set the command rate to 2T but
    you might be able to run your RAM at 1T and that would have an
    increase in RAM bandwidth.

    To the other guy with the 3800 X2, I ran my 3800 at 2400 (240x10) with
    only a minor CPU voltage boost and I set my DDR2-800 to DDR2-666 in
    BIOS which with the overclock the RAM was running at 800 again. With
    that overclock my CPU ran about 30C above room temp and in summer the
    standard AMD heatsink fan was very noisey when the CPU was at 100%
    usage.

    My board has an nVidia chip-set. Originally I overclocked using BIOS
    which switches off Cool n Quiet for the CPU but I experimented with
    nTune and found I could use that to increase the FSB and have CnQ
    still working so when the CPU was idle CnQ would drop the CPU down to
    1200 (5x240) and drop the CPU voltage as well (CPU was still
    overvolted in BIOS). Win-win for me, I had extra performance when I
    needed it and CnQ when I didn't.
    , Feb 14, 2008
    #3
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