Though most people rarely consider airflow within a computer case, it is one of the most critical components of any PC or Server. This is because, in order to maintain the proper operating temperature within the computer case, air must be drawn into direct contact with the chipsets on the motherboard, memory sticks, video cards, and other components.

Airflow is determined by the design of the motherboard, and its placement within the case. Air is drawn into the computer case through an air intake located at the bottom of the front panel of the computer case. Exhaust fans located at the rear of the computer case and in the power supply located at the top of the rear panel, cause a negative pressure inside the computer case, and draw air across the motherboard, which is mounted vertically (tower PCs as shown on right) just behind the air intake. Air is also drawn in through the small openings around hard drives, DVD and floppy drives. (Desktop computer case airflow is generally drawn in from the left front and exits from the back right.)

Some computer cases are designed with ventilation on the sides and top, in order to increase the airflow and exhaust more heat. But, increased airflow does not always mean your components are being properly cooled.

Unfortunately, most tower computers are positioned standing on the floor, where they are most vulnerable to dust and dirt, which hovers in an area about eight inches above the floor. Each time you walk by or sit down at your computer, dust and dirt are kicked up off the floor and sucked into the computer case. This is where the design of the computer case airflow works against you.

As dust and dirt are drawn into the computer case, the airflow draws that dust and dirt directly across the heated computer chips, and through heat sinks on CPUs and  GPUs, which create an electro-magnetic field that attracts the dust and dirt particles. These particles stick to the chips and inside the heat sinks and disrupt the airflow within the computer case. As more dirt builds up, less and less air flows through the heat sinks or comes in contact with the surface of those chips, causing them to overheat and, sometimes, fail.

Many times, when a chip overheats, especially on the graphics card, users get the “blue screen of death” indicating a hardware failure. You can determine quickly if this is a heat issue caused by dust or a hardware failure simply by turning your PC off and then turning it on again after waiting a minute or so. If it’s a true hardware failure, the blue screen will return. If it’s a just a dirty computer, the system will run normally – until, of course, the chip overheats again.

Some people add additional intake and/or (mostly) exhaust fans thinking they can keep their systems cooler by creating more airflow. Or, they think that, by creating positive air pressure inside the computer case, they will prevent dust and dirt from building up inside. However, adding fans can change the airflow, which can direct air away from the components’ chips, causing them to overheat. So, if you are thinking about adding fans, make sure you take the airflow within your particular computer case into account.