Can (PC) liquid cooling keep my room cool?

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.

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.

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.

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.

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!

http://ask.metafilter.com/187170/Can-PC-liquid-cooling-keep-my-room-cool#2694508 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 :)

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.

If there's a sink nearby, the external heat exchanger could have water running on it, and going down the drain.

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.