Can (PC) liquid cooling keep my room cool?

May 31, 2011 8:41 AM

I have a question about liquid cooling my PC, which I guess is not a mechanical question about the process as much as it is a physics question about the nature of heat transfer. I think.

I live in a place with no air conditioning that often gets very warm. Especially in the long summer months.

I know this is probably not helped by the giant desktop computer I keep at my desk, always sitting there and blowing hot air into the room. Of course, I put it to sleep when appropriate, but man, it gets hot.

Now, I'm not concerned about the PC getting too hot - it's weathered several summers here and seems to be in good shape. However, lately I've become interested in investing in a liquid cooling kit for my PC. It seems like it'd be a heck of a lot less noisy, and also it just seems cool and I like cool projects.

My question is, if I install a liquid cooling system, is my computer likely to be spitting out less hot air? To a significant degree? I mean, how does that work? I mean, the heat is not being pulled off the heatsink and blown directly out of the case - instead it's being dissipated by a non-conductive liquid, right? But it still has to go somewhere. I feel like this is stupid, so please be gentle.

So, before I sally forth with a wrong-headed hypothesis, answer me this - if my main concern is the amount of heat being put out by my computer, will a liquid cooling solution help address that?

posted by kbanas to technology (12 answers total)

I believe you're mistaken as to what goes on. Instead of a set of fins on top of hte processor, and wind blowing past them to cool things off, there is liquid (heat-conductive) which carries the heat outside the case and then dumps it. Your computer is still producing the heat; it's just that the heat of the processor is no longer carried by airflow. An analogue would be an air cooled engine, like a VW, which has fins cast into the engine case, vs. a traditional car with a radiator.

Perhaps the bit of information you're missing is that there's a heat exchanger outside the case, which is where the liquid is cooled off.
posted by notsnot at 8:48 AM on May 31, 2011

But it still has to go somewhere.

Right. Liquid cooling systems come with a little radiator, so the heat comes out of that and into the room anyway. So this solution won't help and might actually make the heat problem a little worse, in a couple of ways.

There will usually be a pump to circulate the coolant, and that pump needs power to run, all of which also ends up turning into heat. So that itself will add a little more heat to the room.

Many modern processors have quite sophisticated thermal management stuff going on inside them, and will slow down if they are too hot. If that's happening now and you solve that problem with a liquid cooling system, the processor may suddenly be free to consume more power and produce more heat.
posted by FishBike at 8:49 AM on May 31, 2011

Oh. Yes.

Well. So, the heat is drawn off the processor (in this case) and then just dumped. In which case, there would be absolutely no advantage here.

Stupid project ruiners. The lot of you.
posted by kbanas at 8:51 AM on May 31, 2011 [3 favorites]

Perhaps the bit of information you're missing is that there's a heat exchanger outside the case, which is where the liquid is cooled off.

And this heat exchanger should transmit an equal amount of heat to the atmosphere as an air-cooled system.

However, it's possible that you could locate this radiator external to your room with some well-done piping - this would certainly lower the amount of heat in your location by increasing it elsewhere.

A simpler solution would be to put your computer in hibernate mode every time you step away from it.
posted by muddgirl at 8:51 AM on May 31, 2011

Maybe you could position the computer so that it blows the hot air out of the window? You maybe able to do this with a little bit of shielding or some pipe like clothes-dryers use.
posted by a womble is an active kind of sloth at 8:55 AM on May 31, 2011

A simpler solution would be to put your computer in hibernate mode every time you step away from it.

Absolutely - but when I'm in the midst of a TF2 battle and my wife is playing Warcraft, that's two PCs blasting out hot air, and hibernation is no option!

I like the idea of moving the radiator outside the room - although that's a little beyond my ability right now (or the scope of project I want to tackle). Hopefully we'll be moving soon, and can settle on a place that has the square footage to let me move the computers out of the bedroom!
posted by kbanas at 8:56 AM on May 31, 2011

FishBike said it right: If that's happening now and you solve that problem with a liquid cooling system, the processor may suddenly be free to consume more power and produce more heat.

From what I understand the liquid cooling will be able to transfer heat away a little more efficiently, and therefore allow the computer to kick up a notch and really show you how to play some TF2 :)
posted by zombieApoc at 9:07 AM on May 31, 2011

From what I understand the liquid cooling will be able to transfer heat away a little more efficiently

"More efficient heat transfer" means more heat outside the computer.
posted by muddgirl at 9:12 AM on May 31, 2011

If there's a sink nearby, the external heat exchanger could have water running on it, and going down the drain.
posted by StickyCarpet at 9:16 AM on May 31, 2011

Okay, it might seem silly, but a friend of mine who had a small apartment and four servers running actually connected ducts from the exhaust fans of his computers and vented them directly outside via a window. The big key to making something like that work is negative air pressure, i.e. more exhaust fan power venting out of the system than intake fans. This helps to keep the hot air from leaking out of cracks in the chassis.

I'll admit it was ugly, but it kept his apartment 10-15 degrees cooler during the hottest parts of the summer.
posted by Mister Fabulous at 9:27 AM on May 31, 2011

Another way of thinking about it: if the liquid absorbs more heat from the processor than it dumps to the ambient, the liquid temperature will rise. If it dumps more heat to the ambient than it absorbs from the processor, the liquid temperature will fall. Obviously when you first turn it on there will be a transient and the liquid will warm up a little bit but eventually it will hit some kind of equilibrium: it's not going to rise (or fall) forever. And at that equilibrium point it will be absorbing exactly the same amount of heat from the processor as its dumping to the ambient, i.e. it will just a medium for transport, it doesn't inherently reduce the amount of heat.
posted by Rhomboid at 10:10 AM on May 31, 2011

Why not get a bigger computer fan? That way it can run more slowly, creating much less noise.
posted by Asymptoot at 12:46 AM on June 1, 2011