Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here. Have something to add to the explanation? Sound off in the comments. Source: Three Wire and Four Wire Fan Connectors Note: When connecting a three wire fan to a four pin fan header, the fan is always on there is no fan control.Ī four wire fan connecting to a four pin fan header:Ī four wire fan connecting to a three pin fan header: The four wire connectors are for processor fans with higher power consumption.Ī three wire fan connecting to a four pin fan header: The three wire connectors are for small chassis fans with lower power consumption.

With this type, fan speed is typically controlled by increasing or decreasing the voltage over the power wire.Ī four pin connector is a little different than the three pin connector since it has the extra (fourth) wire used for controlling and sending signals to the fan, which likely has a chip on it that tells it to slow down or speed up (in addition to the other wires the three pin connector has).Ĭhassis and processor fans use either a three wire or four wire connector. The signal wire measures how fast the fan is moving without any controls for the fan’s speed. To maintain positive pressure, you need to have a higher combined CFM for the intake fans than the exhaust fans.SuperUser contributor Homey_D_Clown_IT has the answer for us:Ī three pin connector is basically power (5/12 volt), ground, and signal. When adding fans to a system, maintaining positive pressure within the case can prevent dust from being sucked into any open holes or crevices. Some manufacturers incorporate LED lighting into their fans as well. Larger fans can usually spin at lower speeds and still move plenty of air without making much noise. Motherboard (CPU) 3 Pin Fan Connector Motherboard (CPU) 4 Pin Fan Motherboard AT Backup Battery Motherboard AT LED/Keylock Motherboard IrDA Motherboard PC-Speaker Motherboard Turbo LED Networking.

Some fans even come with built-in LED lights, others are more performance focused such as this Noctua Chromax fan. Thiago Trevisan/IDGįans vary in size, speed, blade shape and color. This information will be on the package or on the product’s information page. The PWM signal from the motherboard sources 5V during the on state of the pulse, otherwise its pulled to ground. Look for one with a high air flow (measured in cubic feet per minute, or CFM) and low noise level (measured in decibels, or dBA). Fans with a diameter of 120mm are typical in newer cases. The most common fan sizes fall in the 70mm to 140mm range, but fans as large as 230mm are becoming more popular.

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