A Guide to Intake/Exhaust Fans and Airflow for Your Desktop Computer

It’s no hidden secret that the key to keeping your computer’s components cool is to use fans. High-end graphics cards have them built in by default, and while processors don’t come with fans directly stuck onto them, failure to add a heatsink after installation will cause heat-related shutdowns in mere seconds!

While you might have no heat-related issues, you might find your system getting a little too warm when performing intense system activities. In this case it might be worth investigating the possibility of adding intake and exhaust fans to your computer.

computer-airflow-fans

When a heatsink removes heat from corresponding components, the hot air tends to linger around and warm up the inside of your PC. This means that the “old air” is being reused by the fans to cool the system which isn’t ideal! The key, therefore, is to add fans that either get rid of this ambient heat or bring in fresh, cooler air to be used. This is the role of intake and exhaust fans.

As for their differences, it’s very simple: Intake fans brings fresh air into the PC, while exhaust fans kick stagnant air out. In coalition with one another, they can help keep your ambient temperatures down. Rather than attaching themselves directly to components, intake and exhaust fans attach to your computer’s case. You may find grills with four screw-sized holes on each corner around your case. These are places where you can install intake and exhaust fans.

They draw power by being plugged in to 3- or 4-pin sockets on the computer’s motherboard. If you’re looking to get fans for your own PC, make sure you understand where these sockets are and how many of each you have on your motherboard.

While simply adding these to your PC may help reduce temperatures, we can use our head and put them in strategic spots on our PCs to get the most out of our cooling!

By using one intake and one exhaust fan, we can perform the following:

  1. Fresh air is brought in via the intake fans.
  2. The fresh air mingles with the system, supplying it with cool air. This cool air is used by heatsinks to extract heat from components and becomes heated air as a result.
  3. The heated air is pushed out of the computer via exhaust fans.

What we have is a simple intake -> extract -> exhaust system, where a computer is consistently fed cool air while heated air is expelled. This is called a computer’s “airflow” and is a great way to make the most of your system’s fans.

The best way to imagine airflow is to think of a stream of air beginning from the intake fans and ending at the exhaust. As such, we want this flow of air to cross over as much of the PC as possible. When implementing intake fans (or purchasing a case with them pre-installed), they go on the front of the PC where there’s less outside obstruction. This means we put the exhaust fans on the back or top of the PC, so the airflow travels through the PC, picks up heat, and carries it out of the system.

computer-airflow-diagram

So now we know how these fans are used to create an airflow within a system. However, if you look for PC fans to put onto your computer case, you’ll see a lot of semi-confusing statistics being mentioned. So, what do they mean?

computer-airflow-specifications

Intake or Exhaust?

You may notice a lot of fans don’t state whether they’re intake or exhaust fans. This may be because they can be either! Not only will the fan work regardless of what side you install toward the case, but on the fan unit itself, it should show you which way it pushes air. This means you can buy two of the same fan. Just install one so it draws air in and the other so it pushes air out.

Case Compatibility

Not all fans are made the same size! If your case has spots for fans to be installed, make sure to measure the horizontal distance between the two slots for the screws and get a fan that matches that size. If you measure the distance between two adjacent screw holes at 120mm, a 120mm size fan will fit. Also, ensure the fan you’re buying isn’t a heatsink for a processor!

RPM

The RPM (Revolutions Per Minute) defines how fast a fan spins. The higher this number, the faster the fan will spin.

CFM

The CFM (Cubic Feet per Minute) of a fan defines how much air it can shift in a minute. The higher this is, the more air the fan will push in, or out, of your system. In this case the more the merrier!

dBA

This is the decibel statistic and represents how loud the fan can get. If quiet fans are a big consideration for you, make sure to pick a fan with a low dBA.

Pins

Most fans come with a 3-pin connector, which will fit into a 3-pin fan plug on a motherboard. However, if your motherboard supports 4-pins, you can try 4-pin fans instead. The extra pin adds speed control to the fan, while 3-pins typically work as fast as they can. Just remember that 3-pin fans can still work on 4-pin connectors – it just won’t be controllable.

When a PC gets hot, using fans is a simple and cheap way of getting the temperatures back down again. However, with a little bit of care, you can get the most out of your money by ensuring the fans create an airflow within your system, using a combination of intake and exhaust fans to do the job.

How important are PC fans for you? Let us know below!

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