Basic (probably dumb) question about cooling and heat output

[homestarmy]

If your processor (or other device that needs to be cooled) is outputting a certain amount of heat, and you put a fan A on it that cools it to a certain temperature, and then you put fan B that cools it to a lower temperature, would there be a difference in the amount of heat that is given off into the environment from one to another (as in, the case or the room)?

I think I need a Physics/Philosophy dual major to answer this one, ha!

 

[letdown427]

The one at the lower temperature would have given off more heat, based on the fact that it has less heat in it...Surely you can see that?

 

[DivideBYZero]

I would imagine the heat energy is the same and the main difference is that more heat energy is dissapated/removed from the heatsink via transfer to air by fan B.

 

[homestarmy]

Originally posted by: letdown427
The one at the lower temperature would have given off more heat, based on the fact that it has less heat in it...Surely you can see that?

But wouldn't the same amount of heat be output over time? That amount that is kept, that is a "one time only" thing, and beside that "one time only" amount, wouldn't the rest be output?

IE if it is 40C and the other is 38C, wouldn't the same amount of heat be generated and expelled except for the amount to get it to 40C at that one point?

Obviously I am not a thermo-physicist.

 

[SaltBoy]

Not a dumb question - I had been wondering the same thing about three weeks ago when shopping for a quieter, albeit less-efficient fan for my CPU.

Yes, the same amount of heat would be generated by the CPU no matter what fan you're using. The fan just helps the heat move from one place (the CPU/heatsink) to another (the case interior). As you know, if there's no heatsink/fan on your CPU, it will overheat and fry. But with the heatsink/fan in place, the CPU is still producing the same amount of heat.

Am I making sense here?

 

[rivan]

The amount of heat generated and dissipated over time is exactly the same. The cooler you keep your CPU, the higher the temperature of the medium used to cool it ends up. Of course, usually there's a LOT of that medium in proportion to the mass of the chip, so to cool a CPU 20 degrees might only bump the air/water/whatever by a fraction of that.

 

[ch33zw1z]

/me humps his zalman 7700-Cu

 

[FoBoT]

Q = -hA(Ts ? T)

http://blowers.chee.arizona.edu/cooking/heat/convex.html

 

[ArchCenturion]

Heat is energy, the electric energy running thru your processor creates heat energy on your processor, the heat sink and fan transport that energy to the surroundings by conduction/convection/radiation.

By adding a second fan, more electrical energy is dissapated, and therefore you will have more heat energy in the system.