Why do CPU fans have 4 wires?

Simply, a 3-wire fan reports its speed, and a 4-wire fan lets regulate its speed by an external signal, usually coming from the motherboard. Technically, a 4-wire fan is called as “4-Wire Pulse Width Modulation (PWM) Controlled Fan”. Intel developed connection standards for 4-wire fans.

What are the 4 wires on a PC fan?

A 2-wire fan has power and ground terminals. A 3-wire fan has power, ground, and a tachometric (“tach”) output, which provides a signal with frequency proportional to speed. A 4-wire fan has power, ground, a tach output, and a PWM-drive input.

Why do computer cooling fans have 3 wires?

The third wire gives your computer a measure of control over that. It reports the speed of the fan back to the computer’s processors, which allows the motherboard to control the speed of the fan by raising the voltage – and speeding the fan – when the extra cooling is required, and lowering it when it’s not needed.

How do 3 wire fans work?

In a 3-wire fan, first two wires are the power supply wires of the fan. The third wire, comes directly from the output of the built-in ‘Hall Sensor’ chip generates output pulses during the fan rotation. With the help of this third wire, a monitoring circuit can ‘see’ the rotation.

Can you put a 4 pin fan into a 3 pin?

FAQ: Can I run 4-pin PWM fans on 3-pin fan headers? Yes! Please note that 4-pin fans can also be connected to your mainboard’s 3-pin fan headers though. When connected to 3-pin fan headers, the fan will run at full speed (unless the mainboard supports voltage based speed control).

What is the yellow wire for on a fan?

Blue and Yellow Electrical Wires Yellow wires are used as switch legs to ceiling fans, structural lights, and outlets paired with light switches, while blue wires are usually used as travelers for three-or-four-way switches.

How do I manually run my cpu fan?

How to Manually Power on CPU Fans

  1. Start or restart your computer.
  2. Enter the BIOS menu by pressing and holding down the appropriate key while your computer is starting up.
  3. Locate the “Fan Settings” section.
  4. Look for the “Smart Fan” option and select it.
  5. Select “Save Settings and Exit.”

Can I connect a 3 wire fan to a 4 wire connector?

Please Note: You can connect a 3 Pin Fan to a 3 Pin or 4 Pin header on the motherboard. The fan connector will have two guides (1) and these will need to line up with the tab (2) that is on the motherboard fan header.

How do you slow down an electric fan?

With a Shaded Pole motor, you can simply reduce the voltage, say with a light dimmer and the motor produces less torque, then with less torque the air friction on the fan blades causes it to slow down, which in turn moves less air.

Why do fan regulators fail?

If that is an issue, check for faulty switch or regulator which can be replaced. If all is working and the issue persists, more than often, the capacitor needs replacing. If this does not start the fan, the winding and motor are most likely to have problems. They either need to be repaired or replaced.

How do I control the speed of a 3 wire fan?

Control of speed of 3-pin fans can ONLY be done by changing the voltage supplied to it on Pin#2, so this system is called “Voltage Control Mode”, or sometimes “DC Mode”. A 4-pin fan is designed for control a different way, by giving it a fixed voltage supply and then a special signal called PWM on Pin #4.

Where does the wire from a cooling fan go?

The red wire from our relay connects directly to the cooling fan, and the black wire from the cooling fan connects to ground, both wires will utilize our supplied fan harness.

What kind of wire does a PC fan need?

The simplest PC fan requires just two wires – one wire provides power (12V), and the next wire is ground (0V). In a 3-wire fan, the extra (third) wire is the ‘tachometer’ signal (Tacho) wire that indicates how fast the fan is running.

What’s the difference between two and four wire CPU fans?

Add a fourth wire, and the fan’s speed can be varied by the motherboard. The simplest PC fan requires two wires. The red wire provides power (+12 VDC), the black wire is ground (0 V). Applying power to will start the fan running full speed.

How does a 3 wire fan connect to a motherboard?

The other time you need to know how the wiring works in a three-pin fan connector is when you need to connect to a four-pin connection on the motherboard. A 4-pin fan uses its first three wires the same way a 3-pin fan does. The fourth wire connects to a circuit on the main board that’s used to control the fan with precision.