PC Airflow Optimization (Optimal PC Fan Configuration)

To optimize the airflow in your PC, it’s best to understand how cooling works inside a computer case. This way, you can set up the cooling fans the best way for any situation.

You can configure the fans in various ways to give you different results. So I will share all of them and point out which one I recommend based on my experience after building hundreds of computers from scratch.

I’ll just mention that it’s easy enough to create decent airflow through the inside of a computer case and get the system temperature down to acceptable levels.

The true challenge is keeping it cool, quiet, and clean as time passes. So that’s what we will be focussing on. A complete understanding so you can configure cooling like a pro.

Here’s a link to my review of the top CPU cooler on the market.

The main three types of case air pressure

We will start by looking at the three ways to configure cooling.

To help you understand my explanation better, here are the two types of fans I will be referring to:

• Exhaust fan: This fan has its blowing side mounted to the wall of the case. It draws air from inside the case and blows it outside.
• Intake fan: The blowing side faces the inside of the case, draws air from outside the case, and blows it inside.

Negative air pressure

Negative air pressure means that more air is going out than in. The exhaust fan(s) have a higher airflow rate than the intake fan(s). And, of course, we are referring to all the fans inside the case as a collective.

Examples include:

• More exhaust fans of the same size or larger than intake fans.
• The exhaust fan spins faster and is the same size as the intake fan.
• The exhaust fan has a higher airflow rate specification than the intake fan.

Side note: The same points listed here can be applied to any fan configuration when comparing airflow rates.

While it is an effective way to cool your system, it can quite often result in more dust being pulled into your case over time. It is also more difficult to add filters to the intake areas of the case that specifically draw air in through them exclusively.

This is because air may be drawn in where the is no place to add a filter.

However, in some unique instances, you could have a situation where a negative air pressure configuration won’t draw in much dust.

These conditions would have to be met:

1. There must be a large enough intake area that is filtered.
2. The filter must have the correct pore size and density.
3. The filter must have the correct cross-flow rate.
4. The computer case cannot have too many intake areas that are unfiltered.

If these conditions are present, it can be argued that the case may remain clean for longer periods of time.

Positive internal air pressure

Positive air pressure means that you have more air being blown into the case than out. The intake fan(s) have a higher airflow rate than the exhaust fan(s).

While having some positive internal case air pressure is good, it is not the best if it’s too excessive.

If a lot of air is being forced into the case with little exhaust airflow, you can find yourself in a position where insufficient air movement occurs.

This results in stagnant air, which can get hot from the internal components and raise the PC’s internal temperature.

Slightly positive air pressure (More balanced)

This is what I have found to be the best in terms of keeping things cool and clean.

Having positive air pressure means that the air will be drawn primarily from your intake fan(s), and as I’ve mentioned, the air is easier to filter.

A standard air filter can be installed in front of your intake fan(s) if your case doesn’t have one to ensure that cleaner and more dust-free air is drawn into your case.

Because the airflow is more balanced (but not equal air pressure), plenty enough air is still exhausted, which means plenty is flowing in and out to help achieve optimal airflow.

This leaves little chance for stagnant air hanging around to warm up and prevents the internal temperature from rising above desired levels.

How to configure the fans

Take a look at the fans that you currently have on your PC. Take note of how many intake fans you have versus the number of exhaust fans.

If you have any that are noisy, disconnect them one at a time until the noise is gone.

You will then be clear on which fans you need to replace. If a fan is noisy from a cold start-up but goes quieter as it spins, be sure to replace it, as it will most likely give you problems later on.

Tip: Do not disconnect crucial fans for hardware components while your computer is running, like CPU or GPU fans for example.

Fan airflow direction

Fan airflow direction is determined by the direction that the fan is facing. Take note of the small arrows stamped on the fan casing to see the rotation direction and the airflow direction.

Some say that the intake side is always the top of the fan blade side, but I find this too generalized and not specific enough compared with the arrow markings on the fan itself.

Assess the number of fans you need

The size of the computer case will dictate how many fans you are able to install to a certain degree.

For most mid-tower cases, you will preferably want around two or three fans on the intake on the front side of your PC and one exhaust fan.

If you have a larger full tower case, three intake fans at the front and one rear exhaust fan would be a good starting point for optimized airflow.

A larger case has more areas where air can be pushed out of the case compared to a smaller mid-tower. So I recommend a minimum of three intake fans to begin optimizing airflow.

Try to stick to the largest type of fan your case can support. You will be very happy you have done this later, so you can enjoy a very quiet system.

Common fan sizes used in computers

Fan Cage Size (Entire Frame)	Between Mounting Holes
40mm	32mm
50mm	40mm
60mm	50mm
70mm	60mm
80mm	71.5mm
92mm	82.5mm
120mm	105mm
140mm	124.5mm
200mm	154mm
220mm	170mm

Also, choose fans with a ball bearing instead of a sleeve bearing. It will last much longer.

In some cases, adding an extra fan at the upper rear of the case can help with keeping the CPU cooler. Not all cases have a fan mount at the top, so it may not be an option.

If you are looking for a premium air CPU cooler, you can take a look at my article on the Noctua NH-D15 chromax.black talks about it more in-depth.

Note: Selecting fans with four wires will allow you to have easier control over them. This will make fan speed control so easy from most controllers even when controlling them from a motherboard.

Configuring the fan control speeds

There are many ways that fans can be controlled. Plenty of manufacturers offer a wide range of products to accomplish this.

If you plan to set them up once and forget about them, simply connecting them to a pin header on your motherboard will do fine.

Most BIOS programs support fan speed adjustments that enable you to adjust the speed curve or allow full automation on the fan speed when the temperature alters inside the PC case.

This is achieved using temperature sensors to get temperature readings.

If you find that your motherboard’s BIOS doesn’t provide the configurable features that you’re after, installing a software application like SpeedFan is an option.

If you want to take things a step further, a fan controller system could be the ideal hardware component to add to the system.

All the fans connect to a module, which also connects to your power supply. The module allows you to consider each fan’s speed based on the temperature readings from the sensors.

They are commonly referred to as PWM fan hubs or simply fan controllers.

More expensive models have a firmware package that can accept programmable profiles to automatically control the fans in relation to temperature readings.

Some even offer touchscreen interfaces on an LCD display that can be mounted into a 5.25-inch drive bay slot.

How to maintain good airflow while keeping everything quiet

Our other article covered how you can keep a computer quiet. In essence, try and install the largest fans you can.

This might go against someone’s first thought: bigger fan blades equal more noise.

While there is truth to that, there are other factors to consider. Fans are driven by motors.

Motors spinning at a higher RPM (Revolutions Per Minute) can generate more noise. And the same holds true for the fan blades moving through the air.

When you use a larger fan, a greater airflow rate can be achieved at a lower RPM. This means that fans only have to spin at a fraction of the speed compared with smaller ones to achieve the same airflow rate.

The other main thing that helps keep your system cooler and quiet is the number of fans you use.

A few more large fans spinning slowly is better than one fan spinning faster to try and achieve proper cooling.

When it comes to fan speed control, the fan is required to spin as fast as needed to keep the internal temperature of the case cool at any given temperature. So it will only spin as fast as needed, reducing unnecessary higher spinning speeds, which generate more noise.

Rubber-mounted fans or fans with rubberized mount areas also add a little extra when trying to keep things quiet. It will lower the amount of vibration produced by the fan.

How to test the PC airflow inside a case

Initially, simply using your hands can tell you a lot straight away. You can get a good idea of airflow by removing the PC case lid and feeling how much air comes in from the intake fan(s) versus the exhaust fan(s).

Some fans have a poor design, and it may seem like they are spinning and doing their job, but the airflow can be poor. This is not ideal, and I recommend replacing those types of fans right away. I found it most likely to happen when an extremely cheap fan was installed.

As for viewing the airflow, that’s if you have a clear case lid or some clear plastic taped to one side of the case, it would be to use some incense. Use about three sticks together and watch where the smoke travels inside the case when it’s going.

If you want to get more serious about testing airflow, airflow meters are available, and you can place them in various locations with your system.

Checking the air filters

For best airflow optimization, check that the filters on your case aren’t too thick. If they are, there is a high probability that air won’t be able to pass through them easily enough, causing poor airflow.

If the filter has pores that are too large, or if the filter is too thin, dust will easily be drawn into your machine. This will make fans, heatsinks, and the inside of your PC case dirty quickly.

Cleaning these components properly is time-consuming. That’s why careful consideration must be made to limit dust entering the system to reduce intervals between cleaning.

There are some mesh-style filters that are fine, but this will probably mean that you will need to clean them more often. Most of the time, this is fine, as they are usually designed for easy removal and reinstallation.

Make sure that there aren’t any obstructions to the airflow

If you look at the airflow path inside the case by looking at where the air is drawn in and where it exists, you want to ensure nothing messes with that flow path.

Hardware like cables can cause flow issues. So always ensure the inside of the case is tidy and free-flowing.

An example of cables obstructing airflow is the unused power supply cables that often get cable ties in a bunch. This is something that is large enough to obstruct airflow and needs to be kept tidy.

Recommended graphics card cooling fan configuration

When it comes to air cooling for your graphics card(s), two main styles of cooling are used by manufacturers. One is a fan blowing on a heatsink with a shroud, and the other is a blower-style fan.

My personal favorite is the blower-style graphics card cooler. This actually takes air from inside the case and blows it outside the PCI slot plate.

I’ve found that it helps reduce the internal computer temperature substantially. However, your graphics card may run slightly hotter, so I won’t recommend this cooling style on a card to overclockers.

If you choose to go with the more commonly used shroud-style cooler, make sure your case can handle the extra heat. So ensuring that enough air flows through your case is paramount.

Tip: Do not use a shroud style card inside smaller cases.

The downside to blower-style coolers would be the noise and temperature. Shroud-style coolers are more common and are efficient at cooling the card but raise the internal temperature of your PC.

The graphics card is the component that generates the most heat in a PC, by far, so consider your options carefully.

If you need to know how to ensure your graphics card fans are working as they should, please read our article on how to speed up your graphics card fans.

Things to consider for water cooling

Having a radiator cooler assembly for your CPU is usually something that an enthusiast would desire, especially for overclocking the hardware.

One common example of this is an AIO (All-In-One) cooler. It’s usually a closed-loop cooler that’s easier to install and maintain.

I recommend purchasing a computer case that caters well to such components in this situation. If you can get filtered air blown by the radiator fans, it will reduce cleaning considerably.

If you aren’t bothered by the cleaning aspect at all, and you are happy cleaning fine radiator fins regularly, move the radiator outside of the case, and you will get the best cooling situation for both the CPU and inside your case.

It will be the supreme choice in all aspects of cooling.

I recommend a front-mounted radiator configuration. The air from outside the case is cooler, allowing better cooling through the radiator fins straight off the bat.

Of course, I’m not talking about situations where the radiator is too small and cannot cope with the amount of heat being passed through it. That is just bad practice and doesn’t come into play here.

The overall internal temperature may be raised slightly depending on the configuration of your custom cooling loop, but it shouldn’t make any significant difference to the rest of your hardware that could end up causing issues.

How many fans does a gaming PC need?

Although your country’s climate or ambient room temperature plays a major factor in this, a minimum of three fans is recommended. Although five or more is better, having two fans bringing in cool air and one drawing air out is the minimal acceptable configuration.

In most situations, five fans are enough to keep enough cool air flowing in and out of the case.

I recommend considering three intake fans in the front and two exhaust fans. You can place one exhaust fan at the back of the case and one at the top as far back as possible. Or simply having the two exhaust fans at the back will do just fine.

Conclusion

As you can see, PC airflow optimization is something that requires some observation and planning. Beyond that, it’s simply common sense to think about how air moves as a result of your fan configuration and case layout.

Always choose quality components when it comes to your cooling and power. It’s the foundation for building a reliable and long-lasting computer. In this article, I break down why the Noctua NH-D15 chromax.black is my recommended cooler.

There is always plenty of debate about which way is better for each component and build. Sometimes it’s not always about achieving the absolute coolest temperature for every single component.

I have found that these airflow optimization techniques are effective enough for cooling while keeping things practical and maintainable.

If you are ever in doubt about which way works better for you with something, try it another way. This is how you learn and become more experienced in setting up machines that don’t overheat and are also practical for everyone to use and maintain.