How To Connect Extra Fans To PC

With most computer cases today, adding more fans is easy enough for most people. Cases generally provide more than enough mounting areas, so you don’t have to worry about your computer overheating.

Our other article about PC airflow optimization discusses how you should set up the airflow and air pressure type. This is a handy first step to understanding before adding more fans.

How To Connect Fans To A PC

Adding fans facing the wrong way or situated incorrectly inside a computer case could detract from your system’s overall cooling strategy.

This can lead to poorer cooling than you had before adding new ones, and I’m sure that wouldn’t have been the desired outcome from anyone.

Important: Always make sure that your computer has been turned off and isn’t connected to power before connecting or disconnecting any fans.

Now that’s out of the way, let’s look at how you can connect more fans to your PC.

Choosing the right fan

If you don’t have your fans already and still need to purchase some, there are a few things to consider.

  1. Choose the correct size for what your case can accommodate.
  2. Cheap fans may not last very long and may produce more noise. So try and opt for something well-known or that has received good reviews.
  3. Fans with only three wires aren’t as easy to control as those with four.
  4. Larger fans are better for reduced noise as they don’t need to spin as fast for reasonable airflow, reducing noise, especially at idle.
  5. Don’t be afraid to geek out a little and compare noise in relation to airflow volume between various models and makes under their respective specifications area.

Various fan connections

There are a few common types of fan connections that are used today. Let’s go over each type, and you will see how they should be connected depending on the type of connection.

How to connect fans to the motherboard

Pin NumberFunction / NameCommon Wire Colors
1Ground Wire (GND)Black
2Positive Power Wire (+12V)Yellow or Red (If the sensor wire (3) is yellow, then this one will always be red.)
3RPM Sensor (Sense)Yellow or Green
4PWM Speed Control (Control)Blue
Motherboard Fan Connector Pin-out
3 pin connector
3 Pin Connector
4 pin connector
4 Pin Connector

Most motherboards include fan connector headers that either have 3 or 4 pins.

The 3-pin header includes a pin for ground power or negative (-), one for positive power (+), and a third pin for an RPM (Revolutions Per Minute) sensor.

The 4-pin header has everything the 3-pin connector offers, plus an extra pin for PWM (Pulse Width Modulation), which can add speed control to your fan without needing an extra speed control circuit. You can easily create speed profiles using your BIOS or third-party software like Fan Control.

All you have to watch out for when plugging a fan connector into the motherboard is that it goes on the correct way. Usually, its housing will match with a clip on the back of the pin header on the motherboard.

Also, double-check that you are plugging the fan connector into the correct pin header. Motherboards usually have the designation name of it on the silkscreen print.

How to connect a 3-pin fan to a 4-pin Molex connector

All is good if your fan has only a 3-pin Molex connector while your motherboard only offers a 4-pin one. Simply align the fan’s connector housing slot to match the shroud clip on the header on the motherboard end.

If you don’t have the luxury of things being like they are supposed to be, match the color of the wires to the correct PIN shown in the pin-out table above.

Note: Pin 1 will always be marked on any circuit board.

How to connect fans directly to the power supply

A 4 pin power supply connector.
4 Pin Power Supply Molex

There are two common ways fans connect directly to a power supply. Either use a standard 4-pin power plug from the power supply or an adapter board that converts the power supply connector to a motherboard-style pin header.

If your fan has a standard 4-pin power supply connector, ensure you have the tapered edges of the plug matching the socket end. This will ensure that you have the plug and socket orientated correctly before attempting to plug them into each other.

When you have a PCB that your power supply connects to, first check that the power supply plug is properly connected to the PCB adapter.

How to connect extra fans to PC.
Power Supply to Fan Pin Header Adapter Board

Then plug your fan into the pin header connection on the PCB adapter the same way as described for a motherboard connector.

Ensure the fan’s plug groove is aligned with the pin header clip.

Using add-on fan controllers

Adding an independent fan controller system is a more desirable option for some enthusiasts. Many models allow for control over each one and, in some cases, can remove frustration when setting up a speed curve profile.

In this situation, follow the instructions of the fan controller system to get it installed into your computer’s case. Some have a touchscreen module that mounts in a drive bay for convenient control and programming.

Your fans will then connect to the controller unit so that the control system can provide the necessary power, take speed readings, and control the fans according to the specifications of the controller system.

Double-check all connections before powering up the computer

Never assume that anything was plugged in perfectly the first time. Check that all the plugs are seated correctly and connected to the correct pins. Never rush! Always proceed slowly and carefully when working on your computer.