Airflow isn’t the most glamorous part of building a gaming PC, but it’s arguably one of the most important. There’s no point buying the most expensive hardware if it ends up throttling due to high temperatures. So, to help you avoid that, we’ve come up with a quick PC airflow guide designed to help you get to grips with this aspect of PC building.
Getting your rig’s airflow right isn’t too difficult. Still, it requires familiarity with PC fan types, fan positioning, and different air pressure setups. If you’re new to setting up PCs, this guide should help you figure out how best to set up the airflow in your current and future rigs.
Choosing the Right Case and Fans
Before we get into the nitty-gritty of PC airflow optimization, it’s critical to discuss the basics of good airflow. Namely, the case you build your rig in and the fans you populate it with.
The most crucial part of good airflow is getting the right case. Solid front panels severely limit airflow, which in turn impacts cooling performance. So, while these sorts of cases (the NZXT H510 and H510 Elite, for example) are great on the eyes, they’re not quite as great for your temperatures.
This isn’t to say that these kinds of cases are unusable. You can still follow some of our tips to try and improve airflow. However, your temperatures will generally be higher than more ventilated airflow cases, even with the best PC fan setup possible.
So, if you’re willing to transplant cases for the best airflow possible (or if you’re building a new rig from scratch), we recommend buying an airflow-focused PC case. These cases have mesh front panels designed to let as much air through as possible, maximizing airflow and reducing overall system temperatures.
Thankfully, you can find airflow cases in almost any price bracket. Budget options like the Phanteks P300A are excellent performers for the price-conscious, while big spenders can look to the Fractal Torrent for class-leading airflow and temperatures.
Check out our guide on the best airflow PC cases for a more in-depth discussion on airflow cases.
The most important thing to know about PC case fans is that there are two types: static pressure and airflow fans.
Static pressure fans are designed to effectively push and suck air through obstacles such as radiators, mesh panels, and dust filters. This makes them great as intake fans, especially if your case has restrictive dust filters or if you’re using liquid cooling.
Airflow fans are designed to push as much air as possible but aren’t great at moving air through obstacles. So they’re much more suited for use as exhaust fans, as they won’t have to deal with filters or intake restrictions there.
While each fan is best suited to a specific task, there’s no real issue with using a fan in a position it’s not suited for. It won’t be optimal, but real-world temperature differences in an air-cooled rig will likely be minimal at best. You’ll want to stick to static pressure fans with radiators, though.
Fan sizes are also important. The larger the fan, the more efficient it is. So, a 140 mm fan needs less RPM to push a similar amount of air as a 120 mm fan, which results in lower noise levels. If noise concerns you, make sure to install the largest fans your case supports.
Configuring Your Case Fans
Airflow in a PC case generally flows in two main directions: front-to-back and bottom-to-top. Front-to-back airflow is the standard, and almost every PC case on the market supports it. Cool air comes in through one (or more) intake fan at the front of your case, while a rear exhaust fan removes the hot air.
Most modern PC cases will also have extra fan mounts at the top and bottom of the case. Top-mounted fans can be both intake and exhaust but are commonly used as exhausts in the top-rear of the case. Bottom mounted fans, in contrast, are almost always configured as intakes. This maintains a bottom-to-top airflow direction and takes advantage of hot air’s tendency to rise.
When installing PC fans, ensure that you get the case fan direction right for intake and exhaust. Almost all case fans follow the same convention: air flows towards the fan’s protective grille. If your fans don’t have any arrows indicating flow direction, it’s safe to assume they follow this standard.
How Many Fans Do I Need?
It might be tempting to go all out with PC fan placement and fill every fan mount in your case to try and brute force your way to good airflow. But that’s really not necessary.
Linus Tech Tips tested a few fan configurations, finding that the classic two-intake one-exhaust fan setup served as a solid middle ground. Adding a single top rear exhaust fan helped reduce CPU temperatures by another three degrees, but that was about it:
Hardware Canucks ran the same test and came up with roughly similar results. In their testing, two intakes and one exhaust fan offered the best balance between CPU and GPU temperatures. Other fan configurations, including a five-fan setup with two intakes and three exhausts, didn’t provide any concrete improvements.
To that end, we’d recommend a two-intake, one-exhaust PC fan configuration for most air-cooled setups. We have an entire article dedicated to answering how many fans a PC should have with even more testing results and unique configurations to consider if you’re curious, but they don’t change our general three-fan recommendation. You likely won’t benefit hugely from anything more, but feel free to experiment if you have the time (and fans).
Case Air Pressure and Dust Management
Cooling isn’t the only thing you need to worry about when settling on your PC fan configuration. Your fan setup influences your case’s air pressure, which allegedly affects how dusty your PC gets. There are three types of case air pressure:
- Positive air pressure is when you have more intake fans than exhaust fans.
- Negative air pressure is when you have more exhaust fans than intake fans, creating a slight vacuum.
- Balanced air pressure is when you have the same number of intakes and exhausts.
The received wisdom is that positive air pressure is ideal since it’s better at keeping dust out of your system. With a positive pressure setup, the air will primarily come in through your (hopefully filtered) fan intakes, which reduces the dust that ends up inside your system.
On the other hand, a negative pressure setup will potentially suck air in through all the unfiltered gaps and holes in your case, such as panel gaps and PCIe slot covers. Since these openings aren’t filtered, the theory is that this will result in a dustier rig.
In practice, though, it doesn’t seem to matter much, if at all. Overclockers ran a torture test of all three pressure setups and found that dust buildup was almost identical between the three.
So, we wouldn’t worry too much about air pressure as far as dust is concerned. A regular cleaning regimen (two or three times a year should be good) and filtered intakes should help you keep on top of dust. Need air filters? Aftermarket magnetic dust filters are plentiful on Amazon at a reasonable price.
Once you’ve settled on your fan configuration and accepted that you’ll have to regularly dust your PC no matter what air pressure you have, it’s time to look at cable management.
Cable management is the skill (and art) of routing and hiding your power and data cables for a clean look in your rig. Bad cable management makes for an ugly build and is often cited as an impediment to good airflow. It makes sense to think that way; after all, that rat’s nest of cables right in front of your intake fans can’t be good for airflow.
The thing is, though, it might not matter that much, depending on your case. This classic Linus Tech Tips video illustrates it perfectly:
Their simulated cable mess didn’t impact temperatures at all, and it took a bunch of boxes (and a Santa hat) before the CPU and GPU showed a significant increase in temperature. The latter is, of course, an unrealistic situation that likely won’t ever happen outside of testing scenarios.
This isn’t to say that cable management is totally unimportant. A good-looking build is a good build, after all. But it’s an important reminder that you shouldn’t stress out unduly about cable management, especially if you’re building in a roomy mid- or full-tower case.
Interested in cable management but unsure how to approach it? Check out our four-step guide to PC cable management.
Positioning Your AIO
Do you fall on the liquid-cooled side of the air vs. liquid cooling debate? If so, your AIO radiator placement is something extra you need to consider when figuring out your rig’s airflow.
With most 240 mm (and larger) AIOs, you’ll likely choose between installing the radiator in the front or top of your case. Both are valid options with their own set of positives and drawbacks, and it’s up to you to decide which works better for you.
Front-mounted radiators tend to be better for CPU temperatures, as it allows the radiator fans to suck in cool, fresh air from outside your case. But this might lead to higher GPU temperatures since the air coming into the case has already been heated up by the CPU radiator.
On the other hand, a top-mounted radiator can harm CPU temperatures if you use an open-air GPU cooler (most GPUs on the market now are of this type). These open-air GPUs throw hot air all around the case, which is then sucked through the radiator cooling the CPU.
Data from The Tech Buyer’s Guru backs this up, showing a significant increase in GPU temperatures with a front-mounted radiator at medium fan speeds. On the other hand, CPU temperatures didn’t differ quite as much between the two AIO CPU cooler positions.
We’d try a top-mounted radiator first, only changing to a front radiator if CPU temperatures seem like they’re getting out of hand.
Getting your rig’s airflow right is one of those tasks that seems tricky at first. But it’s not all that bad, as our PC airflow guide has shown. If you want the best airflow possible, install some high-performance fans (we have a roundup of the best case fans you should check out) and get an airflow-friendly case. Both of those will cover the basics and get you halfway there.
Of course, swapping cases isn’t for everyone. So, at the very minimum, make sure you follow the front-to-back and bottom-to-top airflow directions and install a suitable number of intakes and exhausts. Some cable management won’t hurt, either, even if it might not have as significant an impact on temps as people assume it does. All the best!