Big Cooling Thread

Since PC cooling uses it's own terms, and uses some terms in weird ways, here's some of the stuff you might need to know. This list is by no means comprehensive, it's just to simplify some of the terms you're likely to see here. If you feel something needs added, please PM me.

Air Cooling: Any cooling using airflow from fans.

Ambient temperature: The overall temperature within the room your computer is in. This can have a huge effect on temperature, since you can't cool below the temperature within the environment with normal cooling solutions. (Peltiers, liquid nitrogen, and dry ice are NOT normal.)

Burn-in/Break-in: Essentially, a lot of thermal paste formulas require a certain number of thermal cycles (going to full load and back) to reach maximum efficiency. Either expect temps to drop a bit over time, or use a CPU stress test to bring it up and down over and over for a while.

CFM: Cubic Feet/Minute. Used to determine how much air a fan moves.

Closed loop: A factory sealed liquid cooling system, such as the Corsair H60. Most of these are pretty bad.

Heatsink: Roughly, an assembly of heat-conducting metal rods, with fins to guide airflow.

Liquid cooling: Cooling by using a pump to push liquid (water or non-conductive propylene glycol are common) through a water block and radiator.

Negative pressure: In PC cases, refers to airflow with more air actively exhausted than taken in.

Passive Cooling: Cooling using only heatsinks, with no fans.

Peltier: Nifty little refrigeration type coolers. Kinda outside the purview of this thread.

Positive Pressure: In PC cases, refers to a case with more air actively taken in than exhausted.

Radiator/Rad: A radiator, works like the one in a car (some people actually use small car radiators) used for liquid cooling.

RPM: Revolutions per minute. High RPM tends to equate to higher noise, and more airflow.

TIM/Thermal Paste: Thermal Interface Material. A fun ceramic or metal colloid type stuff used in a (very) thin layer between heatsinks and hot components to keep pesky air molecules from hurting thermal conductivity.

Water Block: A piece of material (generally metal) with high thermal conductivity, with channels through the inside for coolants to flow through, mounted to CPU, GPU, VRMs, RAM, or other heat generating components.

"Standard" PC case airflow will traditionally intake at the front, and exhaust out the back. I'm not entirely sure why this is, although I do remember in the old beige box days, you'd usually only see one fan, exhausting out the back near the CPU, so I'd guess it was for minimal noise with airflow to the hottest part of the PC, without directing hot air at the various drives in the front.

These days, you'll frequently see "gamer" style cases, which is a fancy term for "we found a way to distract cats AND move more hot air than Congress, without functionally cooling anything!" If I haven't made myself clear, a lot of these are actually nothing special, but they have lots of cool lights, and they DO at least move enough air for most people's use, so the main reasons not to get one would be aesthetics, price, or features.

Ok, now, here's some things to consider. First of all: heat rises. No shit, right? Well, if you think about this, most graphics cards just dump hot air into the case, (although some don't), and with standard ATX mounting, this means your heat will, if otherwise left well enough alone, go straight up towards your CPU cooler. Obviously, the warmer the air is already, the less heat it can pick up from the CPU cooler, so this does affect cooling to some degree.

Ideally (for heat alone) you'd want an External Exhaust, or "blower" style cooler on your GPU. These do exactly what it sounds like, they intake air inside the case, guide it through a heatsink, and blow it through an external exhaust. In practice, these have a nasty tendency to be loud as all hell. Little miniature leafblowers on crack. That said, it can help your overall system temps, as well as serving as a nifty little foot warmer during the winter.

Ok, so, let's consider some of the things that we see in cases, and how they affect cooling, since this is supposed to be the basics.

Negative pressure cooling: The advantage to negative pressure (using the "more exhaust than intake" definition) is that it directs the airflow a bit more specifically. The exhaust fans will pull the air towards themselves, which means that no matter what kind of obstacles in the form of cables, drive bays, dead bugs, and empty Dorito's bags you might have, the air will still move towards the places it exhausts. Of course, it does hurt overall airflow a bit, but then, a tornado moves a TON of air, and it's not good for consumer electronics, right?

Positive pressure cooling: Well, frankly, this is kind of uncommon. It's good for... well, in some cases, it limits the ability of dust to build up, and if the case is pretty open, it lets air exhaust really easily. That said, it tends to be a straight up gimmick, although it DOES have uses for air-cooling SLI/CFX external exhaust cards. It also can help maximize air getting to a heatsink, but it's kind of dependent on airflow.

Isolation: generally, the main thing you'll hear of being isolated is the PSU, whether it's completely isolated, or just flipped so it intakes through the bottom/side of the case, isolation is just some means of physically separating airflow for different components. This has the distinct advantage of preventing things like one component's intake stealing air another component needs, or a component dumping heat through a heatsink, although it can sometimes lead to extra noise, as you have air moving through more holes in the case.

Top exhaust: Almost always a partial gimmick, as most people mount CPU coolers to exhaust or intake through the back, so they aren't yanking hot air off their GPU's. Notable exceptions would be certain Silverstone cases, including the RV02/03 which have the entire motherboard tray rotated 90 degrees, intake through the bottom, and exhaust out the top. These also happen to be amazing cases.
Side intake: Also frequently a gimmick, although they can be handy for SLI cooling with blowers, as you frequently don't get much airflow in between multiple GPU's.

Thermal paste has been argued to death by thousands of users across tons of boards, benchmarked, reviewed, and tested to death. The general consensus here is that casual overclockers don't need to worry about it much, as the gains are relatively minimal, and frequently the extra money is better spent on improving the CPU cooler you buy instead.

Even application has been researched, studied, and screamed about millions of times. What's better? One line? Two lines? Spread it yourself, or use pressure from applying the heatsink? What's the best way to remove it? Well, if you want to find tons of technical details, google is your friend, I'm just going to stick with some basics, and give you a couple of links.

http://www.hardwaresecrets.com/article/What-is-the-Best-Way-to-Apply-Thermal-Compound/1303 Tested application of thermal paste. Link at the bottom of the last page to application for direct touch heatpipes. Note, this is less than perfect testing, the main thing that should be taken from it is that less is more in thermal paste.

http://www.hardwaresecrets.com/article/Thermal-Compound-Roundup-October-2011/1396/5 Thermal paste roundup. Not comprehensive, but gives you the idea.

Note that we're looking at 10 degrees Celcius at the MOST. Yes, that can be a lot in CPU's, but application matters considerably more than what you apply. You can buy the best, if you overdo it, just like a stripper overdoing cheap perfume, the results are less enticing than they should be. Your best bet, if you want to buy something better than the basic stuff that comes pre-applied on your cooler (almost every cooler has this) is to buy something from the middle of the pack on performance, and cheap price, and spend the rest of that budget into a better CPU cooler.

More importantly, you should consider whether the paste is conductive or capacitive. Both of these can do serious damage to your hardware if they get on a PCB, so non-conductive is ideal for most users.

To remove thermal paste, you can either buy a fancy little cleaner kit, or invest in a bottle of 80-90% Isopropyl rubbing alcohol and a pack of coffee filters. Try to avoid things like Q-tips, cotton balls, or kleenex, as they can leave shit behind. Avoid water, due to the whole conducting electricity thing, and avoid strong solvents because we like our motherboard the way we bought it.

Note: In case you're wondering, and yes, we've seen this before: No, thermal "paste" does NOT imply you can use it to glue a heatsink on. You STILL NEED TO USE THE MOUNTING HARDWARE PROVIDED WITH YOUR CPU COOLER OR WATER BLOCK.

Arctic silver TIM guide (Courtesy TheToast)
AMD version.

Also, some CPU coolers come with thermal pads pre-applied, rather than proper thermal paste. Thermal pads can contain parrafin (wax) that makes it harder to clean your CPU properly later. If this is the case, you SHOULD remove it and use other thermal paste.

Ok, this argument has been done to death. Casual overclockers do NOT need liquid cooling. If you want it, great, but you don't need it. Simple.

Now if you decide you want liquid, great. I'm happy for you. Here's some things to consider though. First off, most closed-loop liquid coolers are somewhere in the realm of absolute shit, especially when you factor in price. They have all the drawbacks of liquid (can't passive cool in case of component failure, in some cases they have nasty conductive liquids that can leak, cheap pumps are loud as all hell...) and despite all this potential nastiness, they tend to cost as much or more than air coolers with similar performance.

The one thing that can be said for a closed-loop liquid cooler is that it's good if your PC moves around a lot, as a lot of larger heatsinks have the potential to do some serious damage to your motherboard if they get bumped around too much. Even if they don't break anything, bouncing around can cause pins to lose contact on recent Intel chips, which can cause hardware issues (including losing track of memory channels, or failing to boot entirely.)

If you decide to go for a full blown custom loop, the main thing that can be said is this: DO YOUR HOMEWORK. Get good stuff, get advice, and don't get the advice from the people selling you the stuff, because they might just be on comission.

http://www.legitreviews.com/article/1629/6/ A lot of coolers tested, including some closed-loop liquid and some air. Most of these will be fine for the casual overclocker, so compare price to performance and pick what you like.

Some case cooling benchies.
By no means a comprehensive list of cases, just a start. If you have a preferred case, feel free to bring it up, it'll be added.