Interesting argument between friends

Averagesupernova

A large portion of this thread has had discussion that disagrees with you.

uart

I totally agree. I've given up on this thread already. Russ probably needs to post the facts one final time and lock this.

Maybe I could suggest that many of the responders here could then head on over to the general math forum and start a new topic on [itex]0.\dot{9} \neq 1[/itex]. Hurkyl would just love that.

milesyoung

Of course it won't. A heater might be more effective at circulating the air in the room but that doesn't change the fact that all but a few watts of the power the computer draws is heat transfer to its surroundings. At least argue why you think otherwise.

sophiecentaur

That is rubbish, I'm afraid. How is one KiloWatt different from another Kilowatt? The only possible difference in the energy supplied to the room would be in the light power that escapes through the window from the monitor (perhaps a Watt).

We have already been into the fact that supplying 1kW to a room is not the whole story when it comes to making people feel warm but that is not the issue.

Hmm - fools rush in, you know.

Windadct

All I can say is that a 1000W computer - is it's rated value, full power. So just because the rating is 1000W, does not mean you are using all of that 1000W - If you max out the power supply - then ALL of the 1000W it consumes is left as residual heat.

I would also like to add that Sound and EM are not the only ways to consume the energy - think of all of the ways you can do work ( affect a change in a system) and not give off heat. For example all of the ways to convert to Potential Energy - for example a 1000W Battery charger does NOT give off 1000W of heat.

russ_watters

That is self-contradictory: either the numbers are equal or they aren't.

sophiecentaur

Obviously 'rating' is not what counts and a battery charger is a valid exception but that's only finding loopholes in an argument which was dealing with the notion that dissipated energy is somehow different, according to what's written on the front panel label of the equipment.

And, before questioning just how much heat a computer can generate, just consider the vast amount of trouble they have in getting rid of all the heat in a big Server Room. It's a serious problem.

rbj

if the room is windowless and if the room is completely sound insulated (note neither of these conditions are about either the heater or the computer) and if both the heater and the computer have watt-meters attached and both are drawing the same power of W watts, then I guarantee that you're incorrect, Rooney. they will both heat the room exactly the same.

LawRooney

Yeah, I don't see how I would be incorrect. I made no statement whatsoever about an "ideal room" and simply stated that a heater would obviously warm you up better, even if the total amount of heat given off ended up being the same.

Averagesupernova

I suppose you could say that if you are sitting in front of the heater.
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Let me ask you this: Take 4 incandescent light bulbs of 250 watts each mounted on a board. Then take a 1000 watt radiant heater of the same area as the board. Which one do you think will warm you up better?

rbj

well, i just wanted to plug leaks. photons or phonons that leave the room won't heat it. so i wanted to make clear that none were.

and that's incorrect. they're both giving off the same amount of heat.

es1

Your intuition is likely right but your terminology is wrong. What I suspect you're thinking is if I place a computer in one cold room and a (well designed) space heater in another, turn them both on, return in 30 minutes, then the room with the computer will have a lower ambient temp rise.

I suspect this is right because the thermal resistance of the space heater is likely lower than that of the computer case. Or to put it another way, the computer needs to heat itself more than a space heater before it can heat the room so its startup time is longer.

This effect really only matters on short time scales (there needs to be a point where the computer is releasing all the heat it produces or it will continue to rise in temp) and the initial assumption in the thread told us to ignore this effect.

Also, a real computer connected to a 1KW supply likely does not draw constant 1KW as the power supply is sized for the worst, not typical, case. But again, the initial assumption stated in this case the computer does.

http://en.wikipedia.org/wiki/Thermal_resistance

sophiecentaur

Actually, I suspect that a rack of processors consuming at 1kW will need to be very well cooled and the fans will soon be pumping out the heat at the full 1kW rate because they do not want the internal temperature to get more than the optimum. They have to be as good to the stuff inside the boxes as you r heating system needs to be at home - and with a similar thermal time constant.

OmCheeto

I agree with your friend. I have a macbook, and when I installed the SETI^* software, the fan came on. Sounded like a jet engine inside my laptop. I uninstalled the SETI software. Nothing I did before, nor since, has made my fan work that hard.

I have two spare tower PC's that I no longer use, and have considered starting them up in the winter months running the SETI software. I'm a very big fan of cogeneration, (also known as combined heat and computing, CHC )

hmmm.....

I think my battery routinely lasts for 6 hours, so it would appear to be consuming:
4.565Ah * 12.492V / 6 hours = 9.5 watts

Time my laptop battery would survive if my laptop were drawing 1000 watts:

57.0 wh/1000 watts = 3.42 minutes





You're welcome.



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* I do not mean to imply in any way that I am promoting the History Channel.

sophiecentaur

Puts me in mind of Crocodile Dundee, comparing a laptop and an Internet Server "That's not a computer - this is a computer" (knife).

OmCheeto

I've never seen a real Internet Server.

But this is starting to remind me of Thanksgiving, and the fact that I'm a metaphor whore....


Matherole?

I so want to use that in the "How do magnets work" thread.


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/me hides from the donderbolts.

sophiecentaur

Never heard the word Materhole before but, when googling, I found this, totally randomly, on YouTube_Nerdy or what???

Do you think she could be a recruit for PF?