Cool Case Basics

Cooling the case involves the use of strategically placed fans, which direct airflow over hot areas of the system. Typical hot areas that case cooling takes care of are the CPU's immediate area, the cards, and sometimes the peripherals (mainly hard drive). It's kind of pointless to have a nice heatsink and fan on your CPU, only to have the heat remain inside the case. In theory, a heatsink can not cool whatever it touches down past whatever the ambient temperature is. Thus, it's important to keep the general temperature inside the case cool, as well as having proper cooling on individual components.

The ATX power supply

The ATX form factor already provides some airflow, because it places the power supply near the CPU, which has the power supply's fan blowing air over the CPU. The only problem is that by doing so, the air from the power supply blows over the CPU, which is not necessarily the coolest of air! Thus, in many instances it is advisable to have more than just the power supply fan as the means of moving air through the inside of the case.

As a general rule of thumb, you want to try to have as much air moving into your case as air moving out of your case. This can roughly be achieved by using the same number of fans blowing into your case as the number of fans blowing out, but this assumes that the fans that you are using are of equal power. In actuality, you may have two mid-sized fans blowing air in, while there is one larger "exhaust" fan.

Positioning is everything!

The fans must be positioned properly, too. They must be placed in such a way that the air moving inside your case is able to circulate throughout the case, picking up heat from the various "hot spots" inside your system. Then, this newly-hot air has to exit, instead of hanging around inside the case. Obviously, well-placed fans will be instrumental to this airflow.

Generally, the rule of thumb to follow is if you have two fans that are decently far apart in your system, such as a front case fan and your power supply fan, they should be blowing in opposite directions. That is, one fan should be blowing in and the other should be blowing out. However, if there are two fans that are really close to each other, like two fans side by side, you should put them in the same direction. The reason why is because if they were blowing in opposite directions, air that is getting sucked into the case would be sucked out just as quickly by the other fan, yielding very poor overall airflow for the inside of the case. Proper airflow can be achieved by adding a couple of fans to your system. Many case manufacturers realize the need for additional cooling and offer places where fans can be mounted.