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I have a Kill-A-Watt Power meter on my computer that has a GPU mining bitcoins. It draws 500W from the wall outlet.

My question is, is my computer outputting any less heat than an equivalent 500W heater? Or is 100% of the power drawn from the wall converted into heat?

I'm not sure where the energy would go, so my gut reaction seems to say yes. However, the computer is performing other operations with the power, flipping transistors and spinning fans and such. Would it have some less-than-100%-percentage of the power input that is converted to heat then?

If the fans and hard drives and other kinetic components were excluded (say 500W with nothing spinning, all solid state), would it then have the equivalent heat output of the 500W heater or a perfect 500W heat source?

Ehryk
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  • Asked and answered: http://electronics.stackexchange.com/questions/86922/how-much-of-a-gpus-electrical-usage-is-probably-turned-into-a-increase-in-air-t/86923#86923 – Joe Hass Dec 19 '13 at 11:57

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Pretty much all those 500 watts are turned to heat - the motors stop spinning eventually and no energy has been siphoned off for re-use so heat is the 99%+ by-product. Your screen produces light but this is a small fraction of the energy usage. Your internet connection needs a few volts to drive signals down the wire but this again is milli watts. It's pretty much all heat. Speakers - a few watts maybe but most of that gets turned to heat in the speaker - they are not very efficient (less than 10%)

Andy aka
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  • The current in the wires in the internet connection will end up as heat either in the cable or termination, similarly any energy emitted by peripherals as sound or light will become heat when it hits something in the room. There is one place energy may not become heat - if you are writing to a SSD, then the energy stored in the capacitors in the flash representing zeros won't become heat until the flash is overwritten and the caps discharged. – Pete Kirkham Dec 19 '13 at 12:41
  • What about the kinetic energy to spin the fans? Isn't some of that wattage lost to KE? Or are you factoring in that the movement of air will increase it's temperature? – Ehryk Dec 19 '13 at 19:26
  • When you turn your PC off the kinetic energy built up gets converted to heat in the friction of the bearings!!! It's like a 100% efficient car - you use so many joules to get up to 70mph but at the end of the day, it's stood parked on the drive or street and all that energy built up has been lost in heat (through the brakes) in slowing it down. – Andy aka Dec 19 '13 at 19:57
  • I don't turn it off. 2) Even a 100% efficient car, as it travels at ~65 MPH (and assuming a corvette-shaped one) uses about 26 HP to maintain the constant speed. Would not the spinning of the fans be a loss of energy that is not directly being turned to heat (ignoring the slight increase in temperature of the moved air).
    • – Ehryk Dec 20 '13 at 18:10