What is a PWM-Compatible Fan? Precisely Controlling Fan Speed

When choosing a case fan for a custom-built PC, it is common to see products labeled as “PWM compatible” in their product names or descriptions.

PWM is a technology that controls the fan speed. However, to use this feature, the motherboard must also support PWM, so it is important to understand this before selecting parts.

This article explains PWM in custom PCs, how to identify PWM fans, important points, and the benefits of using PWM fans.

Key Points of This Article

PWM is a technology that precisely controls fan speed.
To use it, a PWM-compatible fan and a motherboard with a 4-pin connector are required (most are compatible now).
PWM fans are mainly used for CPU coolers and PC case fans.
3-pin fans can also control speed, but with less accuracy.
PWM fans allow for optimized temperature management.
They help improve quietness and extend fan lifespan.
By increasing speed only when needed, they save power consumption.

This site also explains how to choose other PC parts based on basic knowledge, roles, performance, and compatibility, so please use it as a reference.

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What is PWM in Custom PCs?

PWM (Pulse Width Modulation) is a technology that allows fine adjustment of fan speed, enabling more efficient cooling.

Originally, fan speed could be adjusted by controlling the voltage, but PWM allows for even more precise control.

From the BIOS or dedicated applications, settings such as making the fan speed 80% when CPU usage is 80% (or temperature is 80°C) can be configured.

As shown in the image, it is possible to adjust using a graph and set the fan speed percentage for each specific temperature.

The computer monitors the temperature of the CPU and GPU, and automatically adjusts the fan speed according to those temperatures.

For example, if the CPU temperature is high, the fan speed increases to boost airflow and improve cooling performance.

On the other hand, when the load is low and the CPU temperature is low, the fan speed decreases to make the PC quieter and save power.

PWM-compatible fans are mainly used in air-cooled CPU coolers, radiator fans for water-cooled CPU coolers, and PC case fans.

CPU cooler fans are directly related to CPU temperature, so 4-pin PWM-compatible fans are usually used.

However, case fans that come with PC cases are often not PWM-compatible, so if needed, it is common to purchase and add PWM-compatible case fans separately.

How to Identify PWM-Compatible Fans

There are two main ways to identify PWM-compatible fans:

Check the product name or specifications on the product page
If you have the actual fan, check if the connector is 4-pin

PWM-compatible fans have a 4-pin connector. 3-pin connector fans are not compatible with PWM, but the motherboard can still control their speed to some extent.

However, the control accuracy is lower compared to 4-pin PWM fans.

Therefore, if precise speed adjustment is needed, it is best to choose a 4-pin PWM-compatible fan.

Points to Note When Using PWM-Compatible Fans

When using PWM-compatible fans, the motherboard’s fan connector must be 4-pin.

If the motherboard has a 3-pin connector, the fan can be connected, but PWM speed control will not work, so be careful when choosing a motherboard.

After checking about five recent motherboards, almost all now have 4-pin connectors, so there is little need to worry.

Benefits of PWM-Compatible Fans

PWM-compatible fans offer the following benefits:

Benefits of PWM-Compatible Fans

Highly Accurate Fan Speed Control
Improved Quietness
Optimized Temperature Management
Longer Lifespan
Power Saving

Highly Accurate Fan Speed Control

PWM-compatible fans use pulse width modulation to finely adjust fan speed and optimize cooling efficiency according to usage conditions.

Even fans that are not PWM-compatible can have their speed adjusted by changing the supply voltage using the motherboard or a fan controller, but their accuracy is not as high as PWM fans.

Improved Quietness

PWM-compatible fans only increase speed when necessary, so they are relatively quiet at other times.

During heavy loads, fans will get louder because more cooling is needed.

However, non-PWM fans run at high speed even when cooling is not needed, so PWM fans are generally quieter.

For those who want a quiet environment to focus while working, PWM-compatible fans are recommended.

Optimized Temperature Management

PWM-compatible fans run at low speed when only minimal cooling is needed, and increase speed when the PC gets hot to maintain proper temperature.

This reduces the risk of performance drops or damage caused by high temperatures in parts like the CPU or GPU.

Also, fans do not need to run at maximum speed all the time, so cooling can be optimized as needed.

Longer Lifespan

PWM-compatible fans can adjust their speed as needed, so they do not always run at maximum output.

This reduces the load on the fan, which slows down the wear of bearings and moving parts, and delays motor deterioration, extending the fan’s lifespan.

Power Saving

PWM-compatible fans can adjust their speed as needed, so compared to non-PWM fans, they reduce unnecessary power consumption.

Since the fan does not always need to run at high speed, power consumption can be saved.

However, fan power consumption is not very high to begin with, so it will not lead to a large reduction in electricity bills.

Summary: PWM-Compatible Fans Are Recommended for More Accurate Temperature Management!

By using PWM-compatible fans, it is possible to control fan speed with high accuracy and maximize temperature management and cooling efficiency.

Here is a summary of the key points again.

Key Points of This Article

PWM is a technology that precisely controls fan speed.
To use it, a PWM-compatible fan and a motherboard with a 4-pin connector are required (most are compatible now).
PWM fans are mainly used for CPU coolers and PC case fans.
3-pin fans can also control speed, but with less accuracy.
PWM fans allow for optimized temperature management.
They help improve quietness and extend fan lifespan.
By increasing speed only when needed, they save power consumption.

To check if a fan is PWM-compatible, use the following methods:

Check the product name or specifications on the product page
If you have the actual fan, check if the connector is 4-pin

Also, when using PWM-compatible fans, the motherboard’s fan connector must be 4-pin, but most recent motherboards are equipped with 4-pin connectors.

Therefore, there is no need to worry much when choosing a motherboard.

This site also explains how to choose other PC parts based on basic knowledge, roles, performance, and compatibility, so please use it as a reference.