Picking the right chassis for your build is essential for thermal performance especially with modern components that are now drawing more power and producing more heat as the industry continues to push higher speeds and overclocking limits. Let’s discuss the importance of what we at CORSAIR call, Direct Airflow Path in PC case designs.
When setting up your case fans, having the right balance between intake and exhaust airflow is something to keep in mind. A very common setup would have case fans set to intake from the front panel of your chassis whereas exhaust fans would typically be configured on the top and rear panels.
Pulling fresh cold air through the front panel allows the airflow path to pass directly over your graphics card, CPU, and RAM to keep them cool. Heat naturally rises, so having the exhaust fans on the top and rear panels would help guide the hot air out of the case. Some PC cases like the Crystal Series 680X RGB even have room on the bottom panel where fans can be setup for intake to increase cold airflow.
Looking at an older chassis like the CORSAIR 400R isn’t too different from many modern budget cases and will have permanently fixed drive cages sitting right up against the inside of the front panel.
The CORSAIR 750D took advantage of the emerging trend towards 2.5″ SSDs by allowing you to mount them against the back of the case while featuring removable 3.5″ hard drive cages that could be taken out to allow air to flow in more directly from the front panel fans, it did still support a 5.25″ ODD bay which limited the front panel to just two 120mm fans in the front.
As case design has evolved, massive dedicated drive cages, and ODD bays have largely fallen out of favor due to the increasing popularity of fast M.2 storage solutions and the digital delivery of games/other software. A modern CORSAIR chassis like the CORSAIR 4000D Airflow was designed for airflow (as you could probably tell by the name) with generously perforated cutouts on the front panel and takes advantage of these trends by keeping its single removable drive cage within the PSU shroud and omitting an ODD bay altogether, allowing for direct airflow from the front panel intake fans.
As we mentioned before an older chassis like the 400R and 750D can also be adjusted for better direct airflow by simply removing the drive cages. If you are using multiple drives for your storage, consider switching to 2.5″ SSDs and mount them against the back panel instead. Not only does this solution free up obstructions to the front panel intake fans, but you’ll also be benefitting from faster solid state drives compared to traditional 3.5″ drives.
Another thing to keep in mind is how airflow can affect the pressure inside your case. If you have more intake airflow than exhaust, then you’ll most likely have a positive pressure. Conversely, more exhaust than intake airflow will cause a negative pressure. Generally speaking, positive pressure is better because air will naturally be forced or find its way out of the case through perforations or other openings. That said, it’s best not to have things like unmanaged cable clutter shoved in a corner or stacks of drive cages in front of your intake fans that hinder direct airflow.
In the 680X RGB case build above, if the two bottom fans were flipped around to become intake fans, then the resulting pressure inside this case would most likely be positive instead.
In summary, pick a case without obstructions to your intake fans no matter where they are placed. If you happen to pick a case that does have obstructions to those intake fans, it would be best to adjust and remove those for better airflow. Then finally, have decent cable management so they aren’t cluttered in areas that would restrict airflow path.
If you’d like to learn more about the DC vs PWM fans and how they work, check out the following video from our CORSAIR Lab YouTube channel.