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How To Install Fans in PC [Step-By-Step Guide]

Fans are the cheapest items to assemble in a computer. Regardless of that, their role is important. They help reduce the temperature in the case. Therefore, you need to install fans correctly for proper functioning.

How To Install Fans In Pc

Installing the fan component in the case correctly is essential. If you don’t install and match it well, it can cause the temperature in the computer case to rise. Correct fan assembly in the case will ensure that the overall heat dissipation effect of the chassis works well.

However, you first need to figure out the number, type, and size of fans that your computer needs. This will make it easier to install on your PC without any issues. Otherwise, if your fans aren’t functioning as they should, your computer will slow down subsequently.

1. Determine the Number of Fans in the Case

Determine the Number of Fans in the Case

The size of the case can be divided into ATX or M-ATX. If it is an ATX case, it generally has eight fan installation positions. However, the M-ATX cases have 5-6 fan installation positions. Therefore, check the chassis specification for the specific number of fans needed.

The computer typically has four types of fans. There is the intake fan, exhaust fan, CPU cooling fan, and power supply unit cooling fan. The CPU and PSU fans are normally on their components, but the two case fans, the intake and exhaust are found in different locations.

The intake fans are found towards the bottom of the system, while the exhaust fans are located on the back or top of the case.

2. Check the Fan Size and Speed

Check the Fan Size and Speed

There are generally two fan sizes; 80 mm and 120 mm. There are also some rare sizes, 60 mm and 140 mm. For specific parameters, you can ask the merchant where you purchased the chassis. He will tell you the specific size. If you buy it according to this size, it won’t have a problem.

However, most modern cases use 120 mm fans. Also, remember to find any empty spots on your computer where the fans can be installed on the back, side, top, and front of the tower. In case your case can accommodate large fans, consider getting the larger ones.

Specifically, the 120 mm ones are quieter and more functional. It would help if you also determined whether you want the LED fans or the standard ones.

The speed is the number of revolutions of the fan per minute. The faster the speed, the stronger the wind. Thereby, also check how fast the fans can run.

3. Check the Reasonable Design of the Air Duct

Check the Reasonable Design of the Air Duct

Follow the principle of cold air at the bottom and hot air at the top (heat expansion and contraction). Generally, the bottom and front of the chassis are the air inlet, and the back and top of the chassis are the air outlet. Therefore, try and adjust it according to the number of fans.

i. One fan: There is no doubt that a fan can only be installed on the back of the chassis, next to the I/O baffle.

ii. Two fans: You need to place the fans strategically. Except for the air outlet fan of the rear I/O, the other one can be installed at the bottom of the chassis for air intake or at the front of the air intake. I recommend installing it on the front to form convection with the rear fan. The heat dissipation effect will be better.

iii. Three fans: Except for the air outlet fan at the back, it is recommended to install an air inlet fan at the front and the bottom. Generally, there are cooling vents on the top of the case, and the hot air will evaporate by itself.

iv. Four fans: The inlet fan is installed at the bottom and the front, and the outlet fan is installed at the back and the top.

v. More than four: According to the above, increase in order, starting from the back air outlet.

4. Identify the Wind Direction of the Fan

Wind Direction of the Fan

You need to know the wind direction of the fans for correct installation. There are three ways that you can know.

Tip 1: Check the outside of the fan.

Check the outside of the fan

On the outside-side rim of the fans, you will see the arrows. These are directional arrows. The arrow pointing down shows the direction the fan blades move, and the arrow pointing behind symbolizes the airflow backward.

outside-side rim of the fans

Tip 2: Check the front of the fan

Check the front of the fan

The front side is the intake side, and the behind is the outtake side.

Tip 3: Check the backside of the fan.

Check the backside of the fan

Some crossbars look like an X. Therefore; you are assured that the air comes out in that direction, coming from the front and getting out behind.

5. Connect the Fan's Power Supply Line

Connect the Fan's Power Supply Line

Also, it would help if you chose fans with the right power connectors for your pc. Therefore, open your PC’s case, inspect the power cables and determine what kind of power connector your fan should have. The different connectors include Molex, 3 Pins, and 4 pins.

The power supply line of the cooling fan normally has a 4pin-series. You can easily find them on the wiring of the wire. You need to plug it in.

Unfortunately, I do not recommend connecting the fan's power supply line to the motherboard, which will increase the output voltage of the motherboard. Except for the CPU fan connected to SYS-FAN, the rest of the fans are generally connected to the PWR-FAN interface.

Note that the fan wire should not be in contact with the blade. Otherwise, it may be stuck.

6. Install with a Screwdriver

Install with a Screwdriver

Use a screwdriver of a suitable size for installation, and tighten it appropriately to avoid vibration during rotation. First, you will need to remove the screws that hold the case.

Then locate the point where you connect the fan. The specific points need to have 3 pins on them. Then screw the fan into the specific positions. You should have like two or four screws that hold the fan on.

7. Use a Dust Filter

dust-proof net for pc fan

The air inlet of the chassis is generally equipped with a dust-proof net, which only needs to be stuck on the corresponding baffle. However, it should be removed and cleaned every six months. This will reduce the dust entering the chassis and improve the cooling efficiency of the fan.

Ensure you check your PC for any dust buildup affecting its proper functioning. If there is more dust, that means there is less efficient cooling. Every six months or so, if you are in a dusty area, always open your computer and blow it using some compressed air.

In case it's been a while, you will need to remove the fans and wipe the plastic blades too. The dust filters are efficient in keeping off dust.

FAQ – Frequently Asked Questions

Q. What to do if the fan interface of the motherboard or power supply is not enough

You can use a fan extender. ( I couldn’t find the right resource to answer this question; kindly help me with this question.

Q. Which are the different types of air pressure in the pc?

There is the positive air pressure in which fans draw air into the case and then blow air out of the case. In this, the system has more intake fans than external fans.

For the negative air pressure, the fans blow air out of the case and then draw air in. This causes a slight vacuum effect. This is because the system has more exhaust fans than intake.

There is then the equal air pressure, in which the fans blow in and out an equal amount of air. The system has an equal amount of exhaust and intake fans.


Because after assembling the computer, many wires of the case will be messy, I suggest you use cable ties to bind the wires after assembling the computer to prevent the fan from contacting them. It is important to install the fans on the PC for utmost functionality properly. Ensure you use the right fans for your computer to prevent you from destroying it.