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How to optimise airflow in your PC cabinet?

Optimal airflow on the way

Building a PC is a therapeutic process for most of us at Digit. Spending hours on figuring out the most suitable routes for all the cables is quite normal. Implementing the best cable management is of priority. However, not at the cost of lower cooling performance. Air cooling is the most basic and easiest method to keep your system cool. It is also capable enough to handle basic overclocking. Your PC cabinet will consist of several locations to install cooling fans. Your objective is to ensure that the cabinet has a balanced flow of hot and cool air. If you mess up this balance, you will face problems gradually.

We all know that overheating components is bad news. Populating each and every fan mount with high-speed fans won’t really achieve the best cooling performance. By keeping a few things in mind, you can actually extend the lifespan of your PC components. Here’s our guide to achieving optimal airflow in your cabinet.

PC cabinet layout

The internal design of PC cabinets often keeps changing for the better. Not very long ago, the interiors looked like a claustrophobic person’s worst nightmare. Optical drives and hard drive bays usually took up almost half of the space inside. This design immensely affected airflow since the drive cages restricted a lot of air intake from the front fans. Power supply units used to be installed on the top-rear of the cabinets. Since hot air rises, it was a bad design choice. Next came the painful task of cable management. If you’ve dealt with the ketchup-and-mustard mess of cables from non-modular PSUs, you’d understand. Earlier, cable management was accomplished with just the motherboard plate cutouts. The entangled cables inside the cabinet would end up obstructing the airflow to an extent. Also, they would straight up look messy if your cabinet had a transparent windowed side panel. These designs still exist in cabinets in the lower price range.

Cable management was difficult earlier, so was optimal air cooling.

For the past few years, this has changed. Optical drives aren’t found any more in the majority of the cabinets nowadays. The number of hard drive bays has also reduced over time. This has opened up more room (literally) for additional fans to be installed on the front panel. The power supply is nowadays mostly mounted on the bottom-rear. So now you can add another fan below the top panel. Apart from compact cabinets, you will also find fan mounts on the bottom. However, this isn’t new. New design innovations have also led to cabinets dropping drive cages entirely. Instead, there are suspended drive bays on the motherboard plate on the sides.

This ensures there’s no obstruction at all for airflow from the front intake fans. To prevent the mess of cables affecting airflow, cabinets now have PSU shrouds or compartments. All the extra cables can be stashed in these dedicated zones, away from sight. Some cabinets have dedicated cable routes for the thick cables running behind the motherboard plate. They also have covers or shields to hide them. In conclusion, all these little changes in design have made it easier to implement better air cooling.

External factors

Apart from the challenges present inside the cabinet, optimal airflow also depends on few external factors. The first would be the room’s ambient temperature. In India, the average temperature in the major parts of the country lies between 25-27.5 degrees Celsius. During summers, the temperatures can rise way above 30 degrees. In order to keep your system cool, you could consider getting an air-conditioner or maybe even a basic room cooler. However, it’s a luxury and not necessary.

Another important factor is the location of your case. Placing it inside an enclosed space won’t allow fresh air to enter the cabinet. It would be best to place it in the open either on your desk or directly on the floor. Also, avoid keeping your cabinet over a carpet or rug since it obstructs the PSU fan. If your room has other machines that generate heat, it would be best to move your case to a cooler corner. Essentially, the idea is to keep an unending supply of fresh and cool air around the cabinet.

Different fan mounting locations

In the most basic cabinets, you will find the provision to install two front intake fans, one exhaust fan on the rear and two more exhaust fans on the top. This is generally the case with cabinets in the lower price range. If you go a little higher, you will come across cabinets additionally allowing three front intakes and three exhaust fans on top. Some cabinets might even allow you to add one or two fans at the bottom and side panel. Going up the ladder will only improve the number of fans supported. In the premium range, you will come across enthusiast cabinets such as the Thermaltake WP200 that can accommodate a mind-boggling 40 fans in the cabinet. As we said earlier, more fans don’t necessarily mean a cooler system. In fact, a four or five fan setup is sufficient to keep things cool.

The conventional flow of air inside PC cabinets

Entry-level cabinets have fan mounts on the front, rear and top. Some of them might even include additional mounts at the bottom or on the side panels. Conventionally, the front and bottom fans are used for air intake while the rear and top fans are used for exhaust. The front panel usually has the provision to accommodate the most number of fans in basic cabinets. Every cabinet is designed with a particular airflow pattern. Air will flow from the front to the rear and from the bottom to the top. Since hot air rises, it makes perfect sense to use the top fans as exhaust. If your cabinet has fans on the side panels, your configuration will be dependent on the fans you use. We will now explore the different kind of fans you can install in your cabinet.

Case fan terminology

They are generally available in sizes of 92mm, 120mm, 140mm and 200mm. Cabinets nowadays come with 120mm or 140mm fan mounts, the former being more popular. Before going into details, there are a few fan terms we would like to explain.

  • Fan Speed: It is measured in RPM, that indicates the number of times the fan will rotate in one minute.
  • Cubic feet per minute (CFM): This tells you how much air the fan is capable of moving. The higher the CFM value, the better the fan’s performance.
  • Static pressure (measured in mmH2O): The static pressure value indicates how much force the fan is able to exert on an object. Fans with high static pressure are used when there’s obstruction in front of the fan such as a radiator, heat sink or HDD cage. You will find fans that will prioritise airflow or static pressure, and accordingly, you can buy them based on your configuration.

    The Cooler Master MasterFan Pro 120 Air Pressure is an example of a high static pressure fan
  • Noise level: Although this isn’t important, it’s better to know that higher fan speed will result in higher noise levels. Also, some manufacturers sell quiet versions on both airflow and static pressure fans.
  • Pulse width modulation control (PWM): These fans connect to your motherboard or fan hubs with four pins. Generally, fans connect using three pins. The extra pin allows you to send the PWM signal to the fan. In this way, you can control the speed.

With the important terms out of the way, let’s get into the final segment of this guide.

Setting it all up

Before taking a plunge into fans, let’s start off with cable management. Mid-tier cabinets are generous enough to accommodate extra cables. You can simply hide them without worrying about obstructing airflow. However, entry-level or low-tier cabinets aren’t fun when it comes to cable management. You have to spend some time in routing them appropriately and tying them down with cable ties. Cutouts will be present on these cabinets so it shouldn’t be difficult. Make sure that you’re routing all the PSU cables behind the motherboard plate. You can take advantage of the cutouts to route the specific cables to the front of the motherboard. Essentially, you should avoid connecting the cables directly in the motherboard area. This way you prevent any cable from dangling in the cabinet, obstructing the air intake from the front. Investing a few extra minutes, in the beginning, can save you a lot of time later. Opting for a semi-modular or modular PSU is also recommended. You will end up using only the cables you actually need.

The Corsair RM1000i is a good choice for a modular PSU

Some modular cabinets allow you to remove the drive cages. If you aren’t using them, it would be best to remove them. For example, if you have HDD mounts behind the motherboard plate, you can use them instead of the drive cages to offer better airflow.

Optical drive or hard drive cages are sometimes riveted to the cabinet, which means they have to be cut out. If you do so, make sure to not damage your cabinet. Just make sure you’re not going to change your mind and want an optical drive later. The difference in airflow is significant though, so consider it.

Cabinet manufacturers will generally ship one or more fans inside. One fan is clearly not enough to keep your system cool. Even though there are more fans already installed, you might not achieve the required level of cooling. In that case, you have to opt for aftermarket fans. For this guide, we are looking at air cooling. Hence, our focus will be more towards high airflow fans. Unless your cabinet has an HDD cage obstructing the fan mount. Then you have to go for a high static pressure fan. To keep things easier, let’s go with only high airflow fans.

Dust build up will make your components heat up quickly

Consider a system with three fans for intake and two fans acting as exhaust. Referring to the specifications of the fans, the total CFM of the intake and exhaust fans can be calculated. If you’re using the same fan model, then you can simply count the number of fans to determine whether there’s higher intake or exhaust. If the intake CFM is higher than exhaust, it will result in positive pressure inside the cabinet. This means that more air is being pulled in, than the amount being pushed out. Theoretically, you will have hot air spending more time inside raising the temperature gradually which is negligible. However, positive air pressure will ensure that lower amount of dust enters your cabinet.

A basic diagram of air flow in a negative air pressure enclosure, like your cabinet

Moving on, if the intake CFM is lower than exhaust, we will have negative pressure. Here, more air is leaving the cabinet compared to the air coming inside. This could result in vacuum forming inside the cabinet leading to dust entering from all the tiny holes and crevices. Even dust filters won’t be able to prevent this. But your system will be cooler than what can be achieved with positive pressure. Neutral air pressure is achieved when there is a balance between intake and exhaust. It’s slightly difficult to achieve but the differences are almost negligible. Hence, you have to find a middle ground by trying out different configurations.

You might just say that negative air pressure seems to be the better option. But do remember that dust building up in your components will gradually lead to higher temperatures later. If your surrounding has a lot of dust floating around, it would be best to go for a higher CFM intake configuration.

Final thoughts

By now you must have learned the basics of airflow inside cabinets. You understand how the intake and exhaust work together to keep your components cool. Cable management is something you shouldn’t ignore, especially when you’re dealing with entry-level cabinets. You also came across important specifications of fans that matter while building a PC. Taking things to the next level would be actually calculating the intake and exhaust CFM.

You can go for RGB fans as well since they add insignificant heat (In picture: Thermaltake Riing 12 LED RGB 256 Colors High Static Pressure LED Radiator Fan)

In this way, you can accurately determine whether there’s positive or negative air pressure inside the cabinet. Then you could move on to running benchmarks to measure CPU and GPU temperatures. Accordingly, you can adjust the number of intake and exhaust fans. If you wish to exert more control, you can install PWM fans. These fans will enable you to control the fan speed so that you can fine-tune the air pressure inside. For aesthetic purposes, you can opt for LED fans (RGB fans if you’re that kind of a person) since the heat generated is negligible. The possibilities are endless.

If you consider aftermarket solutions, make sure that you’re reading the specifications before making purchases. It’s true that better cooling will result in better performance in your components. You will also give all your precious components a longer lease of life.

Abhijit Dey

Abhijit Dey

While indulging deep into conspiracy theories surrounding comic book movie plots, he can be found rewatching them looking for easter eggs. Otherwise, his weekends are spent on gaming and browsing memes.