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How many watts for athlon t'bred

Discussion in 'AMD Overclocking' started by Gareth Tuckwell, Oct 12, 2004.

  1. I am doing some heat calculations:

    How many watts (power not heat!) does my Athlon 2400+ Thoroughbred require /
    use at standard clock + volt settings? I think I read 60 watts somewhere,
    but I don't recall where. I also know this info is on the AMD website
    somewhere, but I haven't time to look right now and someone here probably
    knows already!

    Gareth Tuckwell, Oct 12, 2004
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  2. Gareth Tuckwell

    Chip Guest

    What do you mean by that? Power = Heat. Its the same thing.

    Chip, Oct 12, 2004
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  3. Gareth Tuckwell

    iTsMeMa Guest

    Listed as "Maximum Theoretical Power"

    XP2400 TBred Low voltage model 65.3W
    XP2400 TBred 68.3W
    XP2400 Thorton 68.3W

    iTsMeMa, Oct 12, 2004
  4. Gareth Tuckwell

    Chip Guest

    Assuming you don't overclock, of course. In which case it can easily be
    circa 100w

    Chip, Oct 12, 2004
  5. Thanks guys - I am currently undervolting my athlon (using standard 133x15)
    and I was trying to figure out if dropping the volts from 1.65 ro 1.5 would
    actually generate significantly less heat or not!

    I figure that at 2000Mhz power usage is (as above) 68.3W, but dropping from
    1.65v to 1.5v reduces power intake to 56.4W - 17.5% less power, therefore
    17.5% less heat generated. Does this sound reasonable? I don't have exact
    temperatues readings before and after, because I have been messing with the
    fans and the case to quieten things down + improve airflow at the same time!
    I have new quiet PSU and a quiet Samsung drive. I now use just 2 fans
    (rewired to 5v) blowing air around in the case. Air is sucked in past my
    graphics card passive heatsink (radeon 8500), it then floats around for a
    while and is finally blown by 2 fans through my zalman flower cooler and out
    through a new hole in the case next to the processor. It reaches mid to high
    40s under load - I can't get it over 50 degrees and I only have 2 silent
    fanes running, so I am happy with that! Previously it would reach 55+ under
    load, but I don't know if it is the voltage drop or the new fan layout that
    is helping (probably both). I will continue to experiment in my spare time
    (working at the moment!).

    I could draw outside air in through the processor cooler, then out via the
    graphics card, but on exiting the case, the hot air would rise, then be
    drawn back into the processor cooler! I know I could put an intake fan on
    the front to bring cool air from the front of the machine, then add another
    fan to blow (some) air over the grapics card and out the back, but that
    means 2 more fans + more noise. I might consider adding a fan at the front,
    ducting the air to the graphics card and leave it to pump out through the
    processor, but that requires time + some kind of duct!!
    Gareth Tuckwell, Oct 12, 2004
  6. Gareth Tuckwell

    iTsMeMa Guest

    Regarding undervolting your CPU, I have been down that path. My XP2400 on a
    KT133A board was easy to undervolt to 1.5v. It did indeed reduce temps
    approx. 5 - 7 degrees C. However, I noticed occasionally a minor twitch if I
    was pushing the proc (with whatever program) With my current setup (K7V88
    and XP2400) undervolting - without mod - is not possible. Just had to learn
    to live with temps 2 - 3 degrees higher. :}

    Best of luck,

    iTsMeMa, Oct 12, 2004
  7. I have actually just realised I have been running it at 1.475v for several
    days now, of course, as soon as I posted that message it crashed!!
    Coincidence? Maybe!

    I must say though - the hardware monitor (windows) was reporting 1.503v at a
    BIOS setting of 1.475v. Anyone know why the hardware monitor (motherboard
    manufacturer software) reports a higher voltage than I set in the BIOS (same
    for all voltages)? The other voltages 12v, 3v, 5v etc are not absolutely
    spot on either, but I know power supplies have tolerance levels, but I would
    expect the CPU voltage would to run at what it is set in the BIOS?? Anyone
    notice this?
    Gareth Tuckwell, Oct 12, 2004
  8. Gareth Tuckwell

    Steve Wolfe Guest

    Thanks guys - I am currently undervolting my athlon (using standard
    1.5/1.65=0.909, so you can figure on about an 11% reduction in heat.
    It does. Not that the two numbers don't match up (11% vs. 17.5%) because
    the 17.5% number obtained by comparing the theoretical maximum value to a
    real-world value. Had you measured the real-world usage before and after,
    the difference should be much closer to 11%.

    If you really wanted lower power, you could go with a mobile Athlon XP,
    where the max power draws can be as low as 35 watts, and the "power now"
    featured (I believe there's at least one desktop board that supports it)
    will keep actual draws much, much lower when not under load. However, it
    does sound like you've done an outstanding job with what you've got!

    Steve Wolfe, Oct 12, 2004
  9. Gareth Tuckwell

    Chip Guest

    Yes, its very common. The calibration of the temperature monitoring chips -
    and how they interact with the monitoring software - can be pretty poor.
    The bios is perhaps better, but not much. The only real way to be sure is
    to get out your voltmeter. If the 3.3v, 5v and 12v rails look right, you
    can be fairly sure the others will be OK too.

    Just as an aside, I ran my old Barton 3200+ at 1.2v at 11x133MHz for a while
    with a Thermalright Silent Boost heatsink with the fan unplugged. It ran no
    probs at all. 1.1v caused instant Blue Screen of Death.

    Chip, Oct 12, 2004
  10. Gareth Tuckwell

    Chip Guest

    I would think it would be more than 11%. For the purposes of heat
    dissipation we can consider the CPU to be a resistive load. And since P =
    V**2/R, a reduction from 1.65 to 1.5 will yield a 1.5**2/1.65**2 reduction
    in heat. Which is 17.4% Of course the CPU is not purely resistive, but
    this is still a good approximation.
    Or 17.4% in fact.
    The mobiles are good chips, but they only use less power because they run at
    lower voltage, and you can always run a normal XP at lower voltage too. As
    I said in another post, I ran a Barton 3200+ at 1500MHz at only 1.2v with no
    heatsink fan for a couple of months without problem.

    Chip, Oct 12, 2004
  11. Gareth Tuckwell

    Ed Light Guest

    Ed Light, Oct 12, 2004
  12. Read that page very briefly (will spend longer tomorrow) + it looks a bit
    technical - should a relative novice dabble in CPU register settings + such.
    Could I do any permanent damage by using this software??
    Gareth Tuckwell, Oct 12, 2004
  13. Gareth Tuckwell

    Ed Light Guest

    cpuheat only calculates the output according to your input of cpu type,
    speed, and voltage. It's perfectly safe to start up.

    If you're thinking of using cpumsr, read this:


    Ed Light

    Smiley :-/
    MS Smiley :-\

    Send spam to the FTC at

    Thanks, robots.
    Ed Light, Oct 13, 2004
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