1. This forum section is a read-only archive which contains old newsgroup posts. If you wish to post a query, please do so in one of our main forum sections (here). This way you will get a faster, better response from the members on Motherboard Point.

How many watts

Discussion in 'Nvidia' started by Mr. Porter, Apr 11, 2007.

  1. Mr. Porter

    Mr. Porter Guest

    How many watts of heat do 8800 GTXs put out on general

    do they tell us this stuff?
     
    Mr. Porter, Apr 11, 2007
    #1
    1. Advertisements

  2. Mr. Porter

    Phil Weldon Guest

    _____

    The heat generated is equal to the electrical power consumed.

    For one 8800 GTX at standard speed, 145 Watts peak electrical power in, 145
    Watts peak heat out.
    See http://www.xbitlabs.com/articles/video/display/gf8800_11.html .

    Phil Weldon
     
    Phil Weldon, Apr 11, 2007
    #2
    1. Advertisements

  3. Mr. Porter

    SoCalCommie Guest

    Nonsense! All the power isn't wasted (heat is waste), some of it does
    usefull work (~60%). It's not an incandescent light bulb or a space heater.

    SoCalCommie

    "Behind every great fortune is a crime." - Honore de Balzac
     
    SoCalCommie, Apr 11, 2007
    #3
  4. Mr. Porter

    Phil Weldon Guest

    'SoCalCommie', falling into idealism, and failing to seek knowledge from
    practice, wrote:
    | Nonsense! All the power isn't wasted (heat is waste), some of it does
    | useful work (~60%). It's not an incandescent light bulb or a space heater.
    _____

    The 'useful work' in this case amounts to milliwatts.
    The rest is heat. Should you doubt this, try pumping 90 Watts through a
    monitor video in connector.

    Phil Weldon
     
    Phil Weldon, Apr 11, 2007
    #4
  5. Mr. Porter

    Paul Guest

    If 145W of electricity goes into the case, it all comes back as
    heat. Think "conservation of energy". Think like an accountant
    and balance the books. If it doesn't leave as heat, where did
    it go ? I see no additional kinetic or potential energy here.
    So it all left as heat.

    Paul
     
    Paul, Apr 11, 2007
    #5
  6. Where is that work performed? If that 87W is not turning into heat,
    it is being stored somewhere. Where is it being stored?
    Unless you're claiming that there's 87W of power coming out of
    the video connector, you're going to have to explain where it's
    going.

    Yup, except for a very small percentage that's being dissipated
    in the video cable or the monitor's receivers.
     
    Grant Edwards, Apr 11, 2007
    #6
  7. Well a few milliwatts are proably transferred to the monitor
    via the video cable. ;)
     
    Grant Edwards, Apr 11, 2007
    #7
  8. Mr. Porter

    First of One Guest

    Well, if you are going to count that, then include the few watts used to
    drive the cooling fan. :)
     
    First of One, Apr 12, 2007
    #8
  9. Mr. Porter

    Mr. Porter Guest

    Thank you all for the answers and the link especially.

    I water cool my video cards, soon, when the price drops I'll be water
    cooling a couple of 8800GTX's

    knowing 145, gives me a number I can get my system to dissipate. x2 + 65
    for 345 watts
     
    Mr. Porter, Apr 12, 2007
    #9
  10. Those watts turn into heat as well.
     
    Grant Edwards, Apr 12, 2007
    #10
  11. Mr. Porter

    First of One Guest

    Err, nope. Those watts are used to spin the fan blades. (Duh! Electric
    motor.) A tiny amount is lost as heat in the form of bearing friction.
     
    First of One, Apr 13, 2007
    #11
  12. Mr. Porter

    Phil Weldon Guest

    'Mr. Porter' wrote:
    | Thank you all for the answers and the link especially.
    |
    | I water cool my video cards, soon, when the price drops I'll be water
    | cooling a couple of 8800GTX's
    |
    | knowing 145, gives me a number I can get my system to dissipate. x2 + 65
    | for 345 watts
    _____

    Glad we could help.

    I have a web page that hasn't been updated since before the Pentium 4, but
    it does include numbers useful for calculating cooling system capacity (I'm
    not even sure it CAN be updated - my ISP seems to no longer support this
    feature.)

    See http://home.mindspring.com/~pweldon/ .

    Phil Weldon

    | Thank you all for the answers and the link especially.
    |
    | I water cool my video cards, soon, when the price drops I'll be water
    | cooling a couple of 8800GTX's
    |
    | knowing 145, gives me a number I can get my system to dissipate. x2 + 65
    | for 345 watts
    |
    |
    |
    |
    |
    | | > How many watts of heat do 8800 GTXs put out on general
    | >
    | > do they tell us this stuff?
    | >
    |
    |
     
    Phil Weldon, Apr 13, 2007
    #12
  13. And that all of that kinetic energy ends up as heat.
    Everything that's not stored as potential energy ends up as
    heat. That's simple thermodynamics. There's resistive loss in
    the motor, heat loss in the bearings, and shoving the air
    around heats it up.

    100.00% of the energy consumed by a fan turns into heat.

    You're not allowed to destroy energy. You can convert it into
    mass, but that takes something like a particle collider -- not
    a fan on a video card.
     
    Grant Edwards, Apr 13, 2007
    #13
  14. Mr. Porter

    First of One Guest

    Remember the fan isn't just there to stir up the air, it actually propels
    the air through a heat sink and out the back of the PC. The heat sink causes
    a pressure drop due to aerodynamic drag. Volumetric flow rate x pressure
    drop = power.

    Sure, the air eventually slows down, but then the heat is generated outside
    of the PC. The few milliwatts transfered to the monitor via the video cable
    eventually turn into heat as well. Hence the need to define your control
    volume. :)
     
    First of One, Apr 14, 2007
    #14
  15. For some cards that's true. For others, it just stirs up the
    air.
    It wold be interesting to know how much of he power dissipated
    by the fan actually ends up as kinetic energy in the air.
    Unfortunately my fluid dynamics skills are pretty weak.
     
    Grant Edwards, Apr 14, 2007
    #15
  16. Mr. Porter

    GMAN Guest

    There is a power supply calculator here

    http://www.journeysystems.com/?powercalc
     
    GMAN, Apr 18, 2007
    #16
  17. Mr. Porter

    Mr.E Solved! Guest

    Mr.E Solved!, Apr 18, 2007
    #17
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.