So, you want to have sufficient case fans in your PC to avoid overheating and maximize airflow, but you don’t know where to begin. Chin up, in this article, we are going to find the magical number that you are looking for.
Having the right amount of case fans can not only increase airflow but is also the easiest way of extracting more performance from a PC. It is quite appalling seeing how often the significance of case fans is undermined. Now that you are here, you will get to know everything you need about case fans in a PC.
There is a lot to cover, so let’s dive straight into it.
|Why are case fans needed?
|To dissipate heat generated by PC components and prevent overheating.
|How does airflow work?
|Airflow works through intake and exhaust fans. Intake fans pull cool air into the PC, and exhaust fans push hot air out of the PC.
|Minimum number of case fans needed
|At least three case fans are needed for a standard-size computer (two intake, one exhaust).
|Airflow principle for determining fan quantity
|The airflow in CFM (cubic feet per minute) should be equal to the PC case volume in liters.
|PC Case Sizes and Fans needed
|Small Form Factor (SFF): 1-2 fans, Mini-Tower: 2-3 fans, Mid-Tower: 4-5 fans, Full-Tower: 5-8 fans.
|Common case fan configurations
|3 Fans (2 intake, 1 exhaust), 4 Fans (2 intake, 2 exhaust), 5 Fans (2 intake, 3 exhaust).
|Effect of adding more fans
|Decreases the temperature of the PC to a degree, but after a certain threshold, adding more fans leads to diminishing returns.
Why are case fans needed in a PC?
A PC is not complete without case fans. All the components in a PC generate heat, which needs to be dissipated. Every PC component has a thermal limit, for instance, most Intel and AMD processors come with a thermal limit of 95°C. If heat is allowed to accumulate and is not dissipated quickly, the temperature starts to rise.
If the temperature exceeds 95°C, the processor will stop working, and the PC will shut down to save the processor from any catastrophic damage. Such a situation is quite rare, and more often than not, the PC does not shut down but starts to thermal throttle.
Thermal throttling is when a PC or any specific component, such as the processor, cuts performance to reduce heat. Such a measure results in a loss of performance. Thermal throttling is quite common in PCs with not enough fans.
Therefore, a proper mechanism has to be developed for this heat dissipation. The use of case fans is the tried and tested method that many users resort to. The case fans produce airflow, and the exchange of air between the PC and the surrounding is what leads to heat dissipation. It is crucial to have the right number of case fans in order to maximize efficiency and effectiveness.
How does airflow work?
Before we check out the right number of case fans for a PC, it is important to understand the basics of how PC case airflow works. The air flows in a linear direction through the fan, i.e., it enters from one side and blows out from the other side of the fan.
Every case fan has an arrow pointing in the direction the air is going to flow through the fan. It is important that you look for the direction of airflow through the fan because, based on this, the case fans are put into two categories, those being.
The intake fan pulls air into the PC. As a result, these fans are responsible for bringing cool air into the PC. To set up the case fan as an intake, you need to make sure that the arrow on the fan is pointing toward the PC.
As the name suggests, exhaust fans push air out of the PC. These fans operate by removing the hot air that has trapped all the heat of the PC components away from the surrounding. When setting up case fans as an exhaust, the direction of the arrow should be away from the PC.
How many case fans do you need?
There is no one right number as to how many case fans you need. I wish there was because that would have made things very easy. Every PC is different, so the number of case fans you need also varies from one PC build to another.
Generally, every PC needs at least three case fans, out of which two need to be positioned as an intake, and one needs to be positioned as an exhaust. However, for a larger case, you might need more because three fans will not provide adequate airflow that is needed to dissipate heat.
To get the right number of fans for your PC, you need to match the space of the case to the cubic feet per minute (CFM) airflow of the fans. Doing this will mean that hot air in the case is replaced with cool air from the surrounding every minute.
For example, if you have a PC case with a storage capacity of 100L, you will need at least five case fans to cool it properly, as most case fans produce an airflow of 20-25 CFM.
If you are wondering about the difficulty of finding the storage capacity of your PC case, don’t worry use the reference chart below, which contains a generalized list of the different PC case sizes, their estimated capacity, and fans needed for that particular case.
|Case Fans Needed
|Small Form Factor (SFF)
To check the size of your PC case, simply refer to the manufacturer’s website or the Amazon page for your specific case model.
Some common case fan configurations
Here is how to get the most out of the common case fan configurations.
3 Case Fans
If a PC consists of three case fan slots, then two should be configured as an intake and one as an exhaust. Ideally, the intake fans should be placed at the front of the PC case, while the exhaust should be placed at the back of the PC case.
The two intake fans and one exhaust fan configuration create negative airflow. In order to counter the airflow imbalance, the exhaust fan should run at a higher RPM than the intake fans. Usually, this configuration is good for mini-tower cases and may work well in some mid-tower cases as well.
4 Case Fans
In a case with four fan slots, the distribution of intake and exhaust fans should be equal. This means that two case fans each should be used as an intake and an exhaust. This will lead to a neutral airflow, meaning that the air entering the PC case will be the same as air leaving the PC case.
5 Case Fans
If a PC case comes with five case fan slots, the case fans need to be installed in a two-intake and three-exhaust configuration. Ideally, the two intake fans should be 140 MM fans, while the three exhaust fans should be 120 MM fans.
The intake fans need to be placed on the front, while the exhaust fans need to be placed at the top and the back of the case. Since the 140 MM fans provide higher airflow than their 120 MM counterpart, the amount of air entering the PC will similar to the amount of air leaving the PC.
However, if the case only supports 120 MM fans, then the intake fans should be sped up and made to run at a 30% higher RPM compared to the exhaust fans to keep a balanced circulation of air in the PC.
Does adding more fans decrease the temperature?
Adding more fans to a case decreases the temperature of the PC to a degree. However, at a certain threshold, adding more fans leads to diminishing returns because the drop in temperature is not significant anymore.
This is clearly demonstrated by the tests ran by Linustechtips, the video of which is added above. The test set out to find the impact of adding more fans to the PC case and observing temperatures. Testing began with only a CPU cooler installed, and slowly the case fan count was increased to five.
(Add screenshot from linustechtip video showing testing results, the same picture also available on pcbuildinglab)
From the results shown in the picture above, it is quite clear that the temperature dropped significantly when adding more fans up until the fourth fan was added. However, the temperature did not change when the fifth fan was added.
Therefore, we can conclude that adding more case fans leads to a decrease in temperature until the optimal airflow point is reached. Beyond this adding more fans does not have an impact on the temperature of the PC.
Despite there being no definitive answer to the number of case fans needed in PC, it is safe to say that every standard-size computer needs at least three case fans for adequate airflow and cooling. Mind you, this number does not represent the optimal number of case fans that are required because every PC is different.
To find the optimal number of case fans, always remember the airflow in CFM = case volume in Litre’s rule. If the airflow generated by the case fans is equal to the volume of the PC case, then you have the right number of fans in your PC.
Case Fan FAQs
Is 4 case fans too much?
No, four case fans aren’t too much, especially for mid-tower and larger cases. It’s often an ideal number for balancing intake and exhaust (two of each) and ensuring good airflow.
Is 7 fans enough for a gaming PC?
Yes, seven fans should be more than enough for a gaming PC, especially in full-tower cases. Remember to balance intake and exhaust fans to optimize airflow.
Will 2 case fans be enough?
For small form factor or mini-tower cases, two fans (one intake and one exhaust) can be enough. However, for larger cases or high-performance PCs, more fans might be required.
Do I need 3 front case fans?
Not necessarily. Having 3 front case fans can be beneficial for larger cases or if you’re running high-end hardware that generates a lot of heat. However, it’s important to balance this with sufficient exhaust fans.
Is 6 case fans overkill?
Not necessarily. For full-tower cases or PCs with high-performance components, six fans can be beneficial. However, it’s important to ensure they’re properly configured for intake and exhaust.
Are 3 fans better than 2?
Generally, yes. Having an extra fan can help improve airflow and cooling, especially if you’re running more powerful hardware. However, the specific needs may vary based on the PC setup.