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 07-20-2005, 11:23 PM #1 ruffilb Diamond Member   Join Date: Feb 2005 Posts: 5,096 How much does my computer heat up this room? The room I'm in is about 12x15x8, with my computer on a wooden desk at one end. Ambient temperature in the room is, oh, about 35c, say. How much would a computer like this heat up a room like that? I can get more information, obviously, and please tell me how to work out this problem.
 07-21-2005, 12:14 AM #2 Varun Golden Member   Join Date: Aug 2002 Posts: 1,161 How much does my computer heat up this room? find out how many Amps are being drawn from the wall. If you don't know how to do this don't try as you could get killed. Multiply it by the voltage at the wall (100-130 depending on how bad your power is - usually around 120VAC) P=V*I that's really the only way to find out. Temperature of the actual components means little. The only thing that matters is how many Watts of power your computer is using because that is how many watts will be dissapated into the surrounding air.
 07-21-2005, 12:57 AM #3 glugglug Diamond Member   Join Date: Jun 2002 Posts: 5,341 How much does my computer heat up this room? Your temperature sensors are broken. How would your CPU be below the system temp? Also those GPU temps would fry the GPU.
 07-21-2005, 01:02 AM #4 CycloWizard Lifer     Join Date: Sep 2001 Posts: 12,350 How much does my computer heat up this room? What's the maximum power output of your power supply? That's the amount of heat that your computer can add to your room. When dissipated over the entire amount of air present, the effect on temperature is pretty negligible unless you're in a closet. __________________ "Somewhere, in a parallel universe near you, people read books, scientists are treated like rock stars, and beer is not sold in 30 can value packs." --Sign in a bar in Muncie, Indiana Anything is possible when you don't know what you're talking about.
07-21-2005, 12:44 PM   #5
Navid
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How much does my computer heat up this room?

Quote:
 Originally posted by: glugglug How would your CPU be below the system temp?
Quite easily due to the heat generated by the voltage regulator FETs on the motherboard!
The CPU is not the only component that generates heat on a motherboard.

07-21-2005, 12:51 PM   #6
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: Navid Quite easily due to the heat generated by the voltage regulator FETs on the motherboard! The CPU is not the only component that generates heat on a motherboard.
According to the first and second laws of thermodynamics, the CPU can never be colder than the rest of the case during any normal operation. Otherwise, heat from the air within the case would be transferred to the CPU, increasing the temperature. This would continue until the CPU temperature was equal to the case temperature. In addition, the CPU would heat itself to an infinite temperature, since heat cannot be transferred from a low temperature to a high temperature (without a refrigeration cycle anyway).
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07-21-2005, 01:04 PM   #7
Navid
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How much does my computer heat up this room?

Quote:
 Originally posted by: Varun The only thing that matters is how many Watts of power your computer is using because that is how many watts will be dissapated into the surrounding air.
That cannot be true!
Not all of the energy taken by an electronics device is dissipated into heat.
Some of the energy goes to spin the hard drives. Some of it goes to generate an image on the screen. Some of it goes to generate sound from the speakers. Some of the energy goes to transmit a signal to the WLAN etc. etc.

If the computer releases all the energy that it takes into heat, it will not be able to do anything since to so something, it will need energy.

If the computer was 100% efficient, it would not make any heat at all. But, it is not. So, it generates heat. But, to say that the amount of generated heat is equal to the total amount of energy received is too pessimistic.

07-21-2005, 01:05 PM   #8
Navid
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How much does my computer heat up this room?

Quote:
Originally posted by: CycloWizard
Quote:
 Originally posted by: Navid Quite easily due to the heat generated by the voltage regulator FETs on the motherboard! The CPU is not the only component that generates heat on a motherboard.
According to the first and second laws of thermodynamics, the CPU can never be colder than the rest of the case during any normal operation. Otherwise, heat from the air within the case would be transferred to the CPU, increasing the temperature. This would continue until the CPU temperature was equal to the case temperature. In addition, the CPU would heat itself to an infinite temperature, since heat cannot be transferred from a low temperature to a high temperature (without a refrigeration cycle anyway).
You are confusing the case air temperature with the motherboard temperature.

07-21-2005, 01:23 PM   #9
f95toli
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How much does my computer heat up this room?

Quote:
Originally posted by: Navid
Quote:
 Originally posted by: Varun The only thing that matters is how many Watts of power your computer is using because that is how many watts will be dissapated into the surrounding air.
That cannot be true!
Not all of the energy taken by an electronics device is dissipated into heat.
Some of the energy goes to spin the hard drives. Some of it goes to generate an image on the screen. Some of it goes to generate sound from the speakers. Some of the energy goes to transmit a signal to the WLAN etc. etc.

If the computer releases all the energy that it takes into heat, it will not be able to do anything since to so something, it will need energy.

If the computer was 100% efficient, it would not make any heat at all. But, it is not. So, it generates heat. But, to say that the amount of generated heat is equal to the total amount of energy received is too pessimistic.
100% efficiency only means that all the energy is used to do something BEFORE the energy is dissipated as heat; eventually all energy is turned into heat.
The hard drives are spinning, the reason you need to add energy to them is because some energy is lost due to e.g. friction; that energy is converted into heat.

It is the same thing with every device, when you USE energy you are effectely turning into heat.

07-21-2005, 01:23 PM   #10
Varun
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How much does my computer heat up this room?

Quote:
Originally posted by: Navid
Quote:
 Originally posted by: Varun The only thing that matters is how many Watts of power your computer is using because that is how many watts will be dissapated into the surrounding air.
That cannot be true!
Not all of the energy taken by an electronics device is dissipated into heat.
Some of the energy goes to spin the hard drives. Some of it goes to generate an image on the screen. Some of it goes to generate sound from the speakers. Some of the energy goes to transmit a signal to the WLAN etc. etc.

If the computer releases all the energy that it takes into heat, it will not be able to do anything since to so something, it will need energy.

If the computer was 100% efficient, it would not make any heat at all. But, it is not. So, it generates heat. But, to say that the amount of generated heat is equal to the total amount of energy received is too pessimistic.
Actually it all turns into heat, or else it would be self sustained and would require no power.

Your HDD example, why do you think it needs power to keep it spinning? Frictional losses turn energy into heat and the HDD needs more power to keep it spinning.

All of the energy "used" is turned into heat, or else it wouldn't need any.

07-21-2005, 01:34 PM   #11
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: Navid You are confusing the case air temperature with the motherboard temperature.
No, you simply said 'system temperature', which I interpreted to mean case temperature, as I'm sure most others did.
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07-21-2005, 01:37 PM   #12
Navid
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How much does my computer heat up this room?

Quote:
 Originally posted by: f95toli 100% efficiency only means that all the energy is used to do something BEFORE the energy is dissipated as heat; eventually all energy is turned into heat. The hard drives are spinning, the reason you need to add energy to them is because some energy is lost due to e.g. friction; that energy is converted into heat. It is the same thing with every device, when you USE energy you are effectely turning into heat.
So, if I lift a book from the floor and put it on the table, I use energy from my muscles to increase the potential energy in the book (it is at a higher altitude now). Is all the energy that I put into the book converted into heat?

Or, if I charge a capacitor to a voltage, does all the energy I give to the capacitor dissipate into heat?

07-21-2005, 01:42 PM   #13
Navid
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How much does my computer heat up this room?

Quote:
Originally posted by: CycloWizard
Quote:
 Originally posted by: Navid You are confusing the case air temperature with the motherboard temperature.
No, you simply said 'system temperature', which I interpreted to mean case temperature, as I'm sure most others did.
This is a copy of my post:

quote:

--------------------------------------------------------------------------------
Originally posted by: glugglug
How would your CPU be below the system temp?
--------------------------------------------------------------------------------

Quite easily due to the heat generated by the voltage regulator FETs on the motherboard!
The CPU is not the only component that generates heat on a motherboard.

I don't see where I said system temperature.
Anyway, the temperature reported by most utilities as the system or case temperature is really the temperature reported by a sensor on the motherboard. On some motherboards, the voltage regulator MOSFETs get quite hot and the sensor is close to those FETs. So, on many motherboards, the reported system temperature is often higher than the CPU temperature.

07-21-2005, 02:46 PM   #14
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: Navid So, if I lift a book from the floor and put it on the table, I use energy from my muscles to increase the potential energy in the book (it is at a higher altitude now). Is all the energy that I put into the book converted into heat? Or, if I charge a capacitor to a voltage, does all the energy I give to the capacitor dissipate into heat?
Much of your input energy is transformed to heat through your muscles. The muscles work by 'burning calories', which really is nothing but exothermic reactions that supply the energy requirement for the task at hand. Once the energy is used to move your arm and the book, it is lost as heat, else energy would not be conserved. Some of the energy is stored as potential energy in the book, due to the increase in elevation. You're confusing power with energy - they're not the same thing, nor are heat and energy the same thing (though used interchangeably here to cater to the layman). Heat is a mechanism of transferring energy from high temperature to low temperature.
Quote:
 Originally posted by: Navid -------------------------------------------------------------------------------- Originally posted by: glugglug How would your CPU be below the system temp? -------------------------------------------------------------------------------- Quite easily due to the heat generated by the voltage regulator FETs on the motherboard! The CPU is not the only component that generates heat on a motherboard. I don't see where I said system temperature. Anyway, the temperature reported by most utilities as the system or case temperature is really the temperature reported by a sensor on the motherboard. On some motherboards, the voltage regulator MOSFETs get quite hot and the sensor is close to those FETs. So, on many motherboards, the reported system temperature is often higher than the CPU temperature.
Check the bolded part - the part that you quoted previously and were responding to.
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07-21-2005, 03:05 PM   #15
OCedHrt
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How much does my computer heat up this room?

Quote:
 Originally posted by: ruffilb The room I'm in is about 12x15x8, with my computer on a wooden desk at one end. Ambient temperature in the room is, oh, about 35c, say. How much would a computer like this heat up a room like that? I can get more information, obviously, and please tell me how to work out this problem.
Why don't you turn it off for a while and let the temp stabilize, then turn it on and see?
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07-21-2005, 03:21 PM   #16
Navid
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How much does my computer heat up this room?

Quote:
 Originally posted by: ruffilb The room I'm in is about 12x15x8, with my computer on a wooden desk at one end. Ambient temperature in the room is, oh, about 35c, say. How much would a computer like this heat up a room like that? I can get more information, obviously, and please tell me how to work out this problem.
It takes a while, after you make a change to the system (your room thermal system), for the room temperature to stabilize. After it does, the total energy rate (power) transferred to the room will be equal to the total power removed from it.
The PC is one of the components that adds energy. The sun light would be another source.
If you have air conditioning, that would be a component that removes energy from the room.

When your PC is on, you can use what Varun said as a good estimate for the power transferred to the room.

You need to take into account the thermal isolation of the room air from the outside air (double-glass windows?) and the temperature of the outside air.
The amount of air in the room also matters.

Some of the parameters may have no practical impact depending on the values of all the other parameters. For example, if the room is huge and there is good air circulation, the room air temperature with and without the PC will be practically the same.
Or if you have air conditioning with temperature control, the room temperature will be kept reasonably constant by the air conditioning.

07-22-2005, 03:30 AM   #17
Intelia
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How much does my computer heat up this room?

Quote:
 Originally posted by: CycloWizard What's the maximum power output of your power supply? That's the amount of heat that your computer can add to your room. When dissipated over the entire amount of air present, the effect on temperature is pretty negligible unless you're in a closet.
I don't think so . You are supposing that your P/S is operating at its peak power load which is very unlikely. nice try though.

07-22-2005, 12:28 PM   #18
CycloWizard
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How much does my computer heat up this room?

Quote:
Originally posted by: Intelia
Quote:
 Originally posted by: CycloWizard What's the maximum power output of your power supply? That's the amount of heat that your computer can add to your room. When dissipated over the entire amount of air present, the effect on temperature is pretty negligible unless you're in a closet.
I don't think so . You are supposing that your P/S is operating at its peak power load which is very unlikely. nice try though.
Um, that's why I used the words 'can' and 'maximum', nice try though. Let me guess - you straggled in here from the Cases & Cooling Misinformation forum?
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Anything is possible when you don't know what you're talking about.

07-22-2005, 05:32 PM   #19
Intelia
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How much does my computer heat up this room?

Quote:
Originally posted by: CycloWizard
Quote:
Originally posted by: Intelia
Quote:
 Originally posted by: CycloWizard What's the maximum power output of your power supply? That's the amount of heat that your computer can add to your room. When dissipated over the entire amount of air present, the effect on temperature is pretty negligible unless you're in a closet.
I don't think so . You are supposing that your P/S is operating at its peak power load which is very unlikely. nice try though.
Um, that's why I used the words 'can' and 'maximum', nice try though. Let me guess - you straggled in here from the Cases & Cooling Misinformation forum?
************************************************** **********
Sorry it doesn't read like that and its still not possiable because the power supply well not operate at its max. for any extended time and that was not the question to start with . Also who would install a P/S that would only supply the same power as the system draws ? It would be a very unstable system !

07-22-2005, 07:14 PM   #20
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: Intelia Sorry it doesn't read like that and its still not possiable because the power supply well not operate at its max. for any extended time and that was not the question to start with . Also who would install a P/S that would only supply the same power as the system draws ? It would be a very unstable system !
You obviously don't have any idea what this thread is about. Based on your demeanor, I doubt it's worth even trying to tell you. But hey, I'm a glutton for punishment, so here goes nothing.

The OP asked how much effect a computer's heat generation could have on room temperature. A typical engineering approach for such an estimation is to consider the maximum possible energy output of the system, as this will yield the maximum temperature effect of the computer on the room. This maximum energy output will occur at the power supply's peak power draw, since the input power must be output as heat. Thus, the peak power that the PSU can supply will necessarily be the maximum heat output of the computer.

That said, finding the temperature change in the room is still not trivial and dependent on many things, as described above by Navid. It will depend on the materials of the walls, ceiling, floor, any insulation present, and so on. All this because the problem is determining the steady state temperature of the room with and without the heat generated by the computer. As I said in my first post in this thread, it's extremely unlikely that, even at this maximum power consumption/heat output, the computer will have any real effect on the room temperature.
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 07-23-2005, 12:46 AM #21 sundev Golden Member   Join Date: Nov 2004 Posts: 1,092 How much does my computer heat up this room? Turn your computer off and put a thermometer in your room, then leave for a few hours. Come back and see what the temperature is. Then, turn your computer on, leave for a few hours, and come back. See what the temperature is again. That's how much your computer heats up your room. My computer personally heats up my room a lot (with me in it and a monitor on). It can raise the room temperature up to about 30 C (86 F). So, to all those saying it has a negligible effect - it doesn't (at least when combined with the monitor's heat output and my body heat). __________________ Heat
07-23-2005, 01:43 AM   #22
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: sundevb Turn your computer off and put a thermometer in your room, then leave for a few hours. Come back and see what the temperature is. Then, turn your computer on, leave for a few hours, and come back. See what the temperature is again. That's how much your computer heats up your room. My computer personally heats up my room a lot (with me in it and a monitor on). It can raise the room temperature up to about 30 C (86 F). So, to all those saying it has a negligible effect - it doesn't (at least when combined with the monitor's heat output and my body heat).
Like I've said, if you have a small room, large PSU, or other factors, then it could be significant. Of course, you sitting in the room also affects the temperature, since you produce about 150 W of heat. Point being, the result can't be known a priori as asked by the OP because there are simply too many variables. In your case, if you perform the same experiment in the winter, I'd imagine you'd get different results. How much different? Well, that depends - on the materials that your walls are made of, insulation, and so on.
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 07-23-2005, 02:36 AM #23 Rastus Diamond Member     Join Date: Oct 1999 Posts: 4,706 How much does my computer heat up this room? I have no A/C in my house. If I leave my computer on in the afternoon, the whole house gets hot, but if I turn it off and don't use it until later in the evening it's livable in here. Nothing scientific, it's just the way it is. That's only if outside temp is 90+. __________________ "The thing about quotes on the internet is that you cannot confirm their validity." ~ Abraham Lincoln
 07-23-2005, 07:19 PM #24 alphatarget1 Diamond Member   Join Date: Dec 2001 Posts: 5,711 How much does my computer heat up this room? This is an easy thermodynamics problem. I don't have my thermo book with me but you can use the power output from your processor as heat, and use the volume of air at standard temp and pressure. make some assumptions, i.e. heat loss out of the room and stuff.
07-23-2005, 09:53 PM   #25
CycloWizard
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How much does my computer heat up this room?

Quote:
 Originally posted by: alphatarget1 This is an easy thermodynamics problem. I don't have my thermo book with me but you can use the power output from your processor as heat, and use the volume of air at standard temp and pressure. make some assumptions, i.e. heat loss out of the room and stuff.
Well, the entire problem is assumed away if you assume the heat loss from the room. If the heat loss from the room is less than that generated by the computer, the room temperature will rise. If it's equal (can't be greater), then the temperature will be unchanged.
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