The Case for Case Fans

Building a PC today is a simple enough task for most intermediate users, but what about optimizing airflow through the case to keep key components running cool and efficiently? Heat buildup inside of our case can cause major performance problems, or even cause components to fail! With airflow also comes dust, which will always be a factor; even in a clean environment. With a huge variety of fan sizes, speeds, and types, the subject of PC cooling can seem a little overwhelming at a glance! This article will break the subject down into a few simple parts and hopefully get you pointed in the right direction to keep your machine cool and clean.

Fans

First, let’s consider the PC case fan.

Any case fan you will buy will draw air in over the hub of the fan and back. Think of it like an airplane propeller.

Fan Placement

Regardless of whether our PC case is square, slim, micro, mid- or full tower, we will use our case fans to draw cooler air into the case, as well as expel warm air from it. Fans that draw air into the case (Intake fans) should be placed at the front, and if possible, the bottom of the case, while fans that pull warm air out of the case (Exhaust fans) should be placed at the back or top. This will cause a flow of cool air over our internal components, which can produce quite a bit of heat when under load.

Be sure your case is placed on something solid (not carpet) to allow air to flow in if we have bottom-mounted intake fans. This is also important if we have a PSU (power supply unit) mounted at the bottom of the case, which will draw air in from the case, and expel it through the bottom. Allowing the PSU to overheat can cause it to fail completely, which can also damage other components in our PC build. Placing the PC inside of a closed cabinet is also generally a bad idea, since this will limit the amount of air available and can cause heat buildup.

Dusty Business

Now that we’ve covered the basics of ideal airflow for our case, it’s time to consider the enemy of all electronics: dust! Dust can interfere with how our internal components radiate heat, as well as cause fans to fail more quickly. If you’ve built a PC with a window and want to show off the internals (you’re probably a 12-year-old), dust also just looks nasty! Regularly dusting out our case with canned air is important, but we can also look at some different configurations to minimize dust buildup and make our lives a little bit easier.

One option is to create positive air pressure inside our case. This can be achieved by ensuring our intake fans draw more air into the case than our exhaust fans expel it. Positive pressure has the benefit of minimizing the amount of dust that is drawn into the case through the panels and other gaps and grates in the case. Dust filters should be placed over our intake fans.

Negative pressure, achieved by expelling more air from the case than is drawn in, should better cool our internal components in theory, but this is also a trade-off, drawing more dusty air into the case through gaps and grates. We can mitigate the extra dust by placing dust filters over our intake fans as well as over any open grates or gaps in our case.

We can achieve either option by paying attention to the CFM (Cubic Feet per Minute) of the fans we select for our case. Higher CFM fans on our intake than our exhaust will create positive pressure, while the opposite will create negative pressure.

While there are “Static air pressure” fans designed for use with CPU cooling radiators or areas with tightly packed components, the actual difference in performance is negligible and shouldn’t be considered a requirement.