What’s the Difference Between 3-Wire, 4-Wire, and 5-Wire Fans?

When it comes to choosing cooling fans for your devices, you may have noticed that there are 3-pin, 4-pin, and even 5-pin fans on the market. But what exactly are the differences between them? And which one is the best fit for your specific application? In this comprehensive guide, we'll break it all down for you.

2-Wire Fans – Basic Type

· Wires: Power (VCC) + Ground (GND)

· Function: Basic power-on operation, no speed monitoring or control.

· Application: suitable for simple electronics with the simplest cooling requirements.

3-Wire Fans – Speed Monitoring

· Wires:

Red – Power

Black – Ground

Yellow – Tachometer (RPM feedback)

· Function: Monitors fan speed via tach signal; however, it cannot be adjusted in speed directly through the motherboard or controller. They typically operate at full speed or require manual speed adjustment by altering the voltage.

· Application: Suitable for desktops, power supplies, or devices requiring RPM monitoring.

4-Wire Fans – PWM Speed Control

· Wires:

Red – Power

Black – Ground

Yellow – Speed Detection

Blue – PWM (Pulse Width Modulation)

· Function: The standout feature of 4-pin fans is their support for Pulse Width Modulation (PWM) speed control. This technology enables precise adjustment of the fan speed, allowing for intelligent temperature regulation.

· Application: Widely used in a variety of scenarios, including CPU fans, graphics card fans, servers, smart devices, and industrial electronics.

✅ Benefits:

· Quiet Operation: Reduces speed during low-load conditions, minimizing noise.

· Extended Lifespan: Since the fan doesn't run at full speed constantly, its lifespan is significantly extended.

5-Wire Fans – Advanced Control

• Wires: feature an additional "FG" or "ALARM" pin, which serves different purposes depending on the application：
• Function:

· Redundancy Detection: In some cases, this extra pin is used for redundancy checks, especially when two fans are set up as backups for each other.

· Alarm Signals: It can also be used to provide an alarm signal when the fan malfunctions or stops operating.

• Application: primarily used in high-reliability scenarios, such as industrial control systems, telecom equipment, and high-performance servers.

Summary Table

Choosing the Right Fan

✅ Tips:

l  For automatic speed adjustment based on temperature, opt for 4-pin PWM fans.

l  Industrial users who require fan status alarms should consider 5-pin fans.

l  In home use or low-cost scenarios where speed adjustment isn't a priority, 3-pin fans are sufficient.

Now that you have a clear understanding of the differences between 3-pin, 4-pin, and 5-pin cooling fans, you can make an informed decision for your specific needs. If you have any further questions or need assistance in selecting the perfect fan, feel free to contact our professional team. We're here to help you keep your devices cool and running smoothly!