What Are the Functions of the 3-Wire and 4-Wire SanAce Fans?
Categories:
Technology
Author:
rain
Origin:
capital
Time of issue:
2025-09-19 09:19:03.000
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The 3-wire and 4-wire SanAce fans differ in their functions. Compared with the 3-wire fan, the 4-wire fan has an additional PWM (Pulse Width Modulation) speed control function, enabling more precise speed regulation and stronger adaptability.
The specific analysis is as follows:
1. Functions of the 3-Wire Fan
Red wire: Typically the positive power wire, which supplies power to the fan. It usually provides a voltage of 12 volts to enable the fan to operate.
Black wire: Generally the ground wire, connected to the fan’s negative terminal. Its main role is to complete the circuit loop, ensuring the fan works normally. It also provides a certain level of safety protection, such as preventing electric leakage.
Yellow wire: Serves as the speed signal wire (FG or RD). When the fan is running, it sends fan speed information to devices like the motherboard through this wire. This allows the relevant devices to monitor the fan’s operating status, determining whether the fan is working properly and if its speed meets the requirements.
2. Functions of the 4-Wire Fan
Red wire: Functions the same as the red wire in the 3-wire fan—it is the positive power wire that supplies electricity to the fan.
Black wire: Has the same function as the black wire in the 3-wire fan. It acts as the ground wire, connected to the fan’s negative terminal to complete the circuit loop.
Yellow wire: Also serves as the speed signal wire. It is used to send fan speed information to the motherboard or other devices, allowing the system to keep track of the fan speed in real time.
Blue wire: Usually the PWM (Pulse Width Modulation) signal wire, which receives PWM signals sent by the motherboard. By adjusting the duty cycle of the PWM signal, the fan can precisely control its speed. This enables the fan to automatically adjust its speed based on the heat dissipation needs of the device, achieving better heat dissipation effects and energy-saving purposes.
3. What Happens If the Wires of a SanAce Fan (3-Wire or 4-Wire) Are Connected Reversely?
If the wires of a 3-wire or 4-wire SanAce fan are connected reversely, issues such as fan reversal, failure to spin, abnormal speed, or hardware damage may occur. The specific consequences depend on the function of the wires and the way they are reversed. Detailed explanations are as follows:
Reverse Connection of 3-Wire Fans
Reverse connection of positive and negative power wires: If the red positive power wire and the black ground wire are connected reversely, for most SanAce DC fans with built-in protection diodes or circuits, a protection mechanism may be triggered, causing the fan to stop spinning (but the fan is generally not burned out). However, if the fan has no protection circuit, it may reverse direction. Long-term reverse operation may shorten the fan’s service life, and for some fans designed to rotate in one direction only, this may even damage the fan.
Reverse connection of the speed signal wire: If the yellow speed signal wire is connected reversely with the power wire, the fan will be unable to transmit speed information to the motherboard or other devices normally. As a result, the system cannot obtain the fan speed. At the same time, the fan may fail to spin or operate abnormally due to incorrect power connection, and in severe cases, this may damage the fan or related circuits.
Reverse Connection of 4-Wire Fans
Reverse connection of positive and negative power wires: Similar to 3-wire fans, if the red positive power wire and the black ground wire are connected reversely, the fan may stop spinning or reverse direction. Fans with a protection circuit will enter a protection state, while those without a protection circuit may have their service life shortened or be damaged due to reverse rotation. In some cases, short circuits may also occur, burning the fan or other related hardware.
Reverse connection of the speed signal wire: If the yellow speed signal wire is connected reversely with other wires, the system will be unable to obtain the fan speed correctly, which affects the monitoring of the fan’s operating status. It may also interfere with the normal operation of the fan, leading to issues such as abnormal fan speed.
Reverse connection of the PWM wire: If the blue PWM wire is connected incorrectly (e.g., connected to the ground terminal or positive power terminal), the fan will be unable to receive correct PWM signals. Consequently, it cannot automatically adjust its speed based on the device’s heat dissipation needs. Instead, it may run at maximum or minimum speed continuously, which affects heat dissipation efficiency and energy consumption. Long-term abnormal operation may also cause damage to the fan or the device.
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