Quick, tell me what that fan in your computer does besides make noise. For some new modders, fans are an easy way to spiff up a machine. But some don't realize fans have a practical use. They promote air exchange, which can determine, for example, whether your computer crashes during a fevered fragfest. Air exchange refers to the way fans replace your computer's hot air with cool air. The process promotes computer stability and speed by keeping components cool. To find out how to improve air exchange, watch today's show. I'll talk about how air flows through a computer case and show you tips on increasing air exchange.

Open and Blow
Most factory computer cases are restrictive and inefficient when it comes to air exchange. They come with a single exhaust fan in the back of the case or a single inlet fan. The power supply, which generates its own hot air, houses the only other fan. If you're starting with a basic computer case, you have to cut holes and add more fans to increase air exchange. This also means you're going to have a noisier computer (muffle the noise with my noise reduction techniques). Let's look at a few factors affecting the amount of air exchanged.

Push and Pull
Fans need to be able to pull or push the air you want to move. Fans have a CFM (cubic feet per minute) rating, which tells you how much air a fan will cycle. Use the CFM rating to balance the airflow. The size of the fan and how much power it uses affects the CFM. Also, the more power a fan uses, the louder it gets.

Fan Balance
Getting air out of your computer is just as important as bringing air in. Fans need to be balanced for proper air exchange. Fans can easily be balanced by using the same number of intake and exhaust fans. But because fan sizes and CFMs vary, your fans may not be accurately balanced. What matters is the CFM rating. Say your computer has a single 120mm exhaust fan and a pair of 80mm inlets. This setup is fine as long as you know the CFM ratings will match up. If you can't match the CFM rating, install the higher-rated fan as the inlet.

Inlet and Exhaust
Inlet and exhaust openings are key to good airflow. I like to remove the grills to reduce air restrictions, but when I do that, I need to be more aware of what's around my computer. Items can enter the exposed fans and jam them. Placement of the inlet and exhaust makes a difference. Heat rises, so bring cold air in from the bottom of the computer to make exhaust push out the top.

Go Inside
Open a computer and you often see a tangled mess. Arrange the cables so they're neatly bundled. Try to keep the cables out of the middle of the air path. If you can, move your internal components around for better cable placement. If possible, replace the flat cables with rounded ones.

How Does This Help it Stay Clean?
When your PC’s airflow is properly set up, it makes it so dust is less likely to build up in your system. There are many schools of thought on this subject: Negative case pressure, where you have more exhaust than intake, tends to suck in every piece of dust and dirt in the room. Negative pressure also tends to run a little cooler. Positive case pressure, where you have more intake than exhaust, tends to repel dust from coming in the case. Even though positive pressure does not cool as well as negative, the computer staying cleaner will outweigh this. And your cooling should be just as good because when your heatsink is clogged up with dust, not as much air flows across it and therefore it doesn’t cool very well.