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Active cooling when you’re done playing

Last response: in Components
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January 11, 2012 2:47:46 AM

Is there a case that continues to power the fans until the temperature falls once the power is shut off? Anyone who has walked passed a car that has recently been turned off and heard the radiator fan still running is familiar with this active cooling system.

If we consider the process of cooking, lets say a turkey, where it is generally known you only keep it in the oven until it reaches 170 degrees F. Out of the oven the temperature will continue to rise to the desired 180 degrees. If this 10-degree increase happens to a butterball what are the increases to a 1000w+ PSU, an overclocked processor, memory, graphics card, God love us two or three graphics cards? The heat build up inside a partially closed case must be massive when the fans stop spinning.

Then of course there are these huge aftermarket chunks of metal connected to the CPU that retain and transfer all that built up heat, same for the liquid in the radiators although there is a smaller amount directly in contact as apposed to aftermarket cooling towers.

The good thing about an Antec Lanboy case is that you can put a box fan near the side and run it for a few hours after playing.

There seem to be a lot of people experiencing poor gamming performance with newly built systems. Could this be a cause of components overcooking?
a c 111 ) Power supply
January 11, 2012 3:29:58 AM

Why would you want fans that run after the system turns off? Either ways it will cool off but are you saying it is better for the components to be cooled off with a fan when they are shut down?
January 11, 2012 4:39:08 AM

The turkey analogy does not apply here. When you are measuring the temperature of a turkey, you are measuring the center of it. The center is the coolest part, since the heat is being applied externally. Therefore if the center is at 170, if you move half way between the center the temp may be 190. When you take it out of the oven the heat flows from hot to cold, therefore flowing both out of the turkey, and towards the center causing the increased center temp.

In the case of computer components, the part you are "measuring" or care about is the part producing the heat and is therefore the hottest. When you turn them off, the heat generation disappears. They can not under any circumstances get any hotter than what they were at the moment they were turned off. Even though the heat sinks on all of components are "hot" they are still cooler than the processors, and therefore heat can not flow from them to the processors. Heat always flows from hot to cold.
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a b ) Power supply
January 11, 2012 7:14:44 AM

Although I see no reason anyone would want to do this, the best option is to just buy yourself a desk fan. http://247electrical.co.uk/media/catalog/product/f/m/fm...

Just leave the fan pointing at the computer case. However, components cool themselves very very quickly. CPU coolers for example will cool 100% load temps, back down to idle temps in a matter of about 8-10 seconds (depending on the quality of the cooler, of course). In the time it takes for your computer to shutdown and end all current tasks, its likely that components will have already, in that time, cooled themselves back down to idle temps and therefore no further cooling is necessary.

PSU's are possibly the only exception here, "some" PSU's are made so that for around 30 seconds after powering down the fans continue to run to dissipate any built up heat.
January 11, 2012 7:20:38 AM

The only time latent heat is ever an issue is with peltier coolers and extreme overclocking.

Seeing as your not doing this, you won't have an issue with your setup. Just turn it off and be done with it.
January 12, 2012 4:24:55 PM

Do we really know how hot the die is? Do we know how much heat is being transferred while running? Has anyone turned off all fans and taken away all heat sinks to measure how hot components get while running?

Active cooling represents a significant amount of heat loss. While the system is running we only know the temps of actively cooled components. When the power goes off the system loses the ability to transfer heat via convection in other words a heat sink stops working when there is no air circulation. Without a transfer of heat the temp of a die will increase over its previously cooled temp or its true temp will be realized.

Heat doesn’t magically and instantly disappear. Thankfully thermodynamics is a law which means it applies to all objects (relatively) whether it be a server room, inside pc case, turkey… if differences in temperature exist between objects heat will naturally transfer until there is a state of thermodynamic equilibrium. So if your overclocked components are at 50 C and the heat sinks are 40 C only 5 C will transfer, equaling out to 45 C. Heat sinks are designed to keep the operating components at safe temp but notice the keyword “operating” they simply cannot cool when there in no air flowing over the fins. At this point heat will only transfer via radiation or conduction.

The question is will the lower temp spots inside a case be in any danger absorbing this heat and if they are is it a good idea for cases to continue running the fans until temps go down.
a b ) Power supply
January 12, 2012 4:29:59 PM

You speak of thermodynamics but it's obvious you're not getting it. Please refer to Axeman's post.
January 13, 2012 3:20:17 AM

I am a mechanical engineer specializing in thermal systems, I know my heat transfer. I repeat. In the case of turning off your computer, the components CAN NOT get any hotter than what they are turned off. Yes they would cool faster if the fan was still on, but being at say 50C does not hurt them.

What causes components to fail is the heating and cooling cycles, where the components are expanding and contracting do to thermal expansion caused by temperature changes. It is during these expansions and contractions that connections break, due to different materials expanding/contracting at different rates.

Quoting Strongfives
"The question is will the lower temp spots inside a case be in any danger absorbing this heat and if they are is it a good idea for cases to continue running the fans until temps go down."

The hot components do not have enough thermal mass to them to significantly change the temperatures of the other components. The "cool" portions of the board, the relatively cool heat sinks and the air have a thermal mass many times greater than the "hot" components. For example a heat transfer from the "hot" areas that equals a loss of 10C from the "hot components" would increase the temperature of the "cool" components by 1C.
a c 104 ) Power supply
January 13, 2012 2:46:39 PM

If you really want to do some system off cooling although as discussed pointless, heres a method,

One of these (Assuming you are in the U.S. and use 110v wallpower)
http://www.amazon.com/dp/B005VSUY8Y/ref=asc_df_B005VSUY...
^This plugs into a seperate wall/extension socket obviously
Pack of fans as desired and a fancontroller if you want to adjust their speeds manually,
fit fans as desired, when turning pc off, leave that running for five minutes or however long you wish, then turn off that as well,
you can make it complicated by adding timer or sensor switches but that is the basic kind of thing you are after for 'system off' cooling I reckon,
Moto
!