A wee head scratcher fpr a Saturday night.

[halox]

I am having a conversation with a few guys about this subject. See what you think. It is throwing up some strange responses.

The air temperature in a sealed room with a PC with 1 x 290X running a benchmark software for 2 hours is:

A) less with air cooling the 290X.
B) less with water cooling the 290X
C) the same no matter how it's cooled.

 

[mantadog]

The obvious answer is C, but I'm not sure if were taking into account modern GPU's being able to overclock higher with better cooling. If that's the case then the room would be (theoretically) hotter on the water cooling. Just by virtue of the fact that the card is working harder because of the coolers ability to remove heat more effectively.

If the card is running at stock speed and no overclocks then the heat output is the same so both should heat the room equally.

If the room was small enough and was 100% sealed against heat loss like a thermos flask, soon enough you would see no impact between water and air cooling. They are both using air to cool the card and I guess the air would soon heat up to the point the GPUs would be forced to shut down.

That's my thoughts. be interesting to see what comes up.

 

[halox]

The obvious answer is C, but I'm not sure if were taking into account modern GPU's being able to overclock higher with better cooling. If that's the case then the room would be (theoretically) hotter on the water cooling. Just by virtue of the fact that the card is working harder because of the coolers ability to remove heat more effectively.

If the card is running at stock speed and no overclocks then the heat output is the same so both should heat the room equally.

If the room was small enough and was 100% sealed against heat loss like a thermos flask, soon enough you would see no impact between water and air cooling. They are both using air to cool the card and I guess the air would soon heat up to the point the GPUs would be forced to shut down.

That's my thoughts. be interesting to see what comes up.

My thoughts exactly although I didn't bother with the overclocking statement. I was arguing this fact as the person who brought this up stated his room is now cooler, watercooling the card. I informed him that it will be exactly the same whether water or air cooling. The only difference being that when watercooling there is no need for a fast airflow to make up for air cooling inefficiencies. Perhaps he was sitting in the line of the hot air before when air cooling. Whereas now, the hot air does not need to be moved so rapidly perhaps giving false impression of a cooler room. Others have got in on the argument and it is probably 50/50 for the people saying A or C. Good fun though. The only thing that's cooler is the component being cooled as the water is far more effective as the heat carrying molecules are more densely packed than air.

I described it like an air conditioner in the middle of a room. Cold air coming out the front and hot air coming out the back. If the air conditioner is 100% efficient then the average room temperature would not change. In real life though nothing is 100% efficient so the room in actual fact would heat up in this case. Good fun!

 

[steaky360]

I'd have agreed with you both.

If this was a theoretical room and a theoretical problem (perfect world and conditions etc.) then regardless of how you cool the card the room could only get warmer due to conservation of energy? If the card's performing and generating heat as it does so then regardless of the method for removing the heat the room would have to get hotter due to heat transfer from the card into the room?

Maybe I've misunderstood the question

 

[halox]

I'd have agreed with you both.

If this was a theoretical room and a theoretical problem (perfect world and conditions etc.) then regardless of how you cool the card the room could only get warmer due to conservation of energy? If the card's performing and generating heat as it does so then regardless of the method for removing the heat the room would have to get hotter due to heat transfer from the card into the room?

Maybe I've misunderstood the question

Yeah, it will always get warmer. That was never in question. The main question was: Will it get warmer faster with air cooling (A) or water cooling (B) or they both heat the room up at the near enough the same rate (C). Some people say, water keeps the room cooler. Others say it makes no difference to the room temperature.

This conversation was taken from facebook page:

https://www.facebook.com/photo.php?...6020510911&type=1&theater&notif_t=photo_reply

 

[mantadog]

My thoughts exactly although I didn't bother with the overclocking statement. I was arguing this fact as the person who brought this up stated his room is now cooler, watercooling the card. I informed him that it will be exactly the same whether water or air cooling. The only difference being that when watercooling there is no need for a fast airflow to make up for air cooling inefficiencies. Perhaps he was sitting in the line of the hot air before when air cooling. Whereas now, the hot air does not need to be moved so rapidly perhaps giving false impression of a cooler room. Others have got in on the argument and it is probably 50/50 for the people saying A or C. Good fun though. The only thing that's cooler is the component being cooled as the water is far more effective as the heat carrying molecules are more densely packed than air.

I described it like an air conditioner in the middle of a room. Cold air coming out the front and hot air coming out the back. If the air conditioner is 100% efficient then the average room temperature would not change. In real life though nothing is 100% efficient so the room in actual fact would heat up in this case. Good fun!

I wasn't sure if this was a sort of thought experiment along the lines of if you have a truck full of birds, does it weight more/less or the same if they fly instead of standing the floor. Since we are talking real world the answer is fairly simple, the energy output is the same so while it might take fractionally longer to heat up (as the water absorbs the energy) the end result is identical.

Oh yeah, and for anyone interested the truck weighs exactly the same, the birds flapping wings cause downward pressure on the floor of the truck equal to the weight of the bird doing the flapping.

 

[halox]

I wasn't sure if this was a sort of thought experiment along the lines of if you have a truck full of birds, does it weight more/less or the same if they fly instead of standing the floor. Since we are talking real world the answer is fairly simple, the energy output is the same so while it might take fractionally longer to heat up (as the water absorbs the energy) the end result is identical.

Oh yeah, and for anyone interested the truck weighs exactly the same, the birds flapping wings cause downward pressure on the floor of the truck equal to the weight of the bird doing the flapping.

I remember watching that one on Mythbusters. Does that mean the weight of the earth never changes too? IE All the planes are grounded then they all take off. I am purely talking about planes here nothing else.

 

[ubuysa]

I agree that after 2 hours the room temperature will be the same regardless of what cooling you use. What might well be different is how fast the room heats up. Intuitively I'd have expected a water cooled system (which can get the heat away faster) to heat the room quicker than if you're just air cooling. But that wasn't the question.

 

[steaky360]

I remember watching that one on Mythbusters. Does that mean the weight of the earth never changes too? IE All the planes are grounded then they all take off. I am purely talking about planes here nothing else.

I think the Earth is a more complex system than a truck and I'm not sure if you can apply the same logic. I would say if the Earth was a sealed system and nothing else changed, then yes it's weight should remain the same regardless of the planes.

Sidenote: The writer of xkcd does some excellent 'thought experiment' type blogs on 'what-if xkcd'. There are some amusing outcomes and comparisons https://what-if.xkcd.com/1/. I'm not trying to distract from this conversation with that though, just pointing it out, its pretty funny at times.

 

[ubuysa]

I think the Earth is a more complex system than a truck and I'm not sure if you can apply the same logic. I would say if the Earth was a sealed system and nothing else changed, then yes it's weight should remain the same regardless of the planes.

Sidenote: The writer of xkcd does some excellent 'thought experiment' type blogs on 'what-if xkcd'. There are some amusing outcomes and comparisons https://what-if.xkcd.com/1/. I'm not trying to distract from this conversation with that though, just pointing it out, its pretty funny at times.

[pedant mode on]

It could be argued that the Earth has no weight at all, all it has is mass. Weight is just a measure of the gravitational attraction of the Earth on object close to it.

[pedant mode off]

 

[steaky360]

It could be argued that the Earth has no weight at all, all it has is mass. Weight is just a measure of the gravitational attraction of the Earth on object close to it.

I guess that would depend on your definition of Earth. There'd certainly be some weight from the oceans, gasses, landmasses floating about on the mantel (which constitutes for most of the Earths gravity due to its massive density relative to everything else around it).

 

[halox]

[pedant mode on]

It could be argued that the Earth has no weight at all, all it has is mass. Weight is just a measure of the gravitational attraction of the Earth on object close to it.

[pedant mode off]

That's why I said weight and not mass. Exactly the same as the truck and birds scenario. The weight changes the mass does not. I know what you mean though but its just hypothetical.

 

[ubuysa]

I guess that would depend on your definition of Earth. There'd certainly be some weight from the oceans, gasses, landmasses floating about on the mantel (which constitutes for most of the Earths gravity due to its massive density relative to everything else around it).

[pedant mode back on again]

I have to disagree. As I said, weight is really just a measure of gravity. You probably know that the weight of an object varies a little depending on where on the Earth you weigh it (because the Earth is neither homogeneous nor a perfect sphere). Weight is not a physical property, mass is. The Earth, oceans, gasses, etc. all have mass as a physical property but they only have weight because of the local (i.e. Earthbound) effect of gravity. For example, if you could take an object weighing exactly 1kg at the surface to the very centre of the Earth it would have no weight because the gravity of the Earth would be pulling equally in all directions. Similarly if you could take it into empty space (although there is no such thing) it would also have no weight because there would be no gravity pulling on it. So if you take the entire Earth system (the Earth, oceans, gasses etc.) it has a mass but the only weight it could said to have is that which it gets from the gravitational attraction of the Sun and the other planets.

[pedant mode off again]

 

[mantadog]

Hmm I think I might have started something here... oopsie

Air behaves just like a fluid so think of it this way. You have a tank of water, pretty much a sealed system so unless you splash some out it will stay the same weight. Say the tank has a scale underneath it if you were to put a submarine in the tank and sink it the whole system would have the same weight if you were somewhere in the middle or even on the surface. The only thing that makes it slightly counter intuitive when dealing with air is that you don't often see things floating on air, but the physics are no different to the water tank.

If you had a 1km high 25m wide sealed cylinder of air you could put a hot air balloon in it and it would give the same reading on a scale placed underneath they cylinder with the balloon resting on the ground as it would with it at 1km high. Take the air out of the cylinder and you have nothing for the balloon to support its weight on so it cant climb.

the whole earth is a bit more complicated because you start dealing with weight vs mass as someone pointed out above but the basic principal is the same. While i'm here, ubuysa the proper formatting for pedant mode is [PEDANT] [/PEDANT]

 

[ubuysa]

... While i'm here, ubuysa the proper formatting for pedant mode is [PEDANT] [/PEDANT]

It's always good to learn new things. Thanks!

 

[sparki]

My guess:
A or B depending on which cooling motor draws more power (P=IV) during the two hours. Presuming all else equal.

 

[mantadog]

My guess:
A or B depending on which cooling motor draws more power (P=IV) during the two hours. Presuming all else equal.

yeah but I think the point is were not talking about that, just the overall effect of removing heat via air or water.

 

[halox]

If you had a 1km high 25m wide sealed cylinder of air you could put a hot air balloon in it and it would give the same reading on a scale placed underneath they cylinder with the balloon resting on the ground as it would with it at 1km high. Take the air out of the cylinder and you have nothing for the balloon to support its weight on so it cant climb.

That's a good way of looking at it. It would be exactly the same for a plane.

 

[pr1s0ner]

The PC generates the same amount of heat regardless of how efficiently you cool it. The cooling just stops the heat from getting to sensitive parts. So definitely C. (That is ignoring whether either of the cooling options actually generates more heat than the other)

 

[Androcles]

[pedant mode back on again]

I have to disagree. As I said, weight is really just a measure of gravity. You probably know that the weight of an object varies a little depending on where on the Earth you weigh it (because the Earth is neither homogeneous nor a perfect sphere). Weight is not a physical property, mass is. The Earth, oceans, gasses, etc. all have mass as a physical property but they only have weight because of the local (i.e. Earthbound) effect of gravity. For example, if you could take an object weighing exactly 1kg at the surface to the very centre of the Earth it would have no weight because the gravity of the Earth would be pulling equally in all directions. Similarly if you could take it into empty space (although there is no such thing) it would also have no weight because there would be no gravity pulling on it. So if you take the entire Earth system (the Earth, oceans, gasses etc.) it has a mass but the only weight it could said to have is that which it gets from the gravitational attraction of the Sun and the other planets.

[pedant mode off again]

Sounds about right to me, the Earth has plenty of mass, but would only have weight if an external gravitational force was working, just like if you take an object into space it would have mass but no weight due to there being no gravitational effect, weight is simply a measurement of gravity effecting an object, hence why someone in space is weightless.