What is a 3-Pin Connector?

By Amy Goetzman | June 21, 2022

Meet the Connector: 3-Pin Connectors

While many connectors feature a configuration with three pins, the term 3-pin connector is often used to refer to a simple white nylon pin receptacle with three tin contacts that is typically used in small, low-power computing products, most notably computer fans. The connector and its contacts can be purchased separately, together, or in an assembly with three color-coded stranded wire leads (power, signal, and ground).

StarTech fan with 4-pin connector for pulse modulation control, from Allied Electronics.

These connectors are also sometimes called motherboard fan connectors, or just fan connectors. They are available with three or four pins; the fourth handles fan speed control via pulse width modulation (PWM). A 3-pin connector can be mated with a 4-pin connector but the PWM function will be disabled. These connectors may be referred to as SYSFAN and CPUFAN in some resources. The SYSFAN connector is used to connect PC case fans, while the CPUFAN connector is used for the fan attached to the CPU heat sink. These connectors are easy to connect and disconnect, an advantage, as fans are frequently upgraded or replaced.


JST PH series 3-pin connector with cable assembly from Digi-Key Electronics

They are also — erroneously — called Molex connectors because of their resemblance to a very similar product designed in the 1950s by Molex Connector Company, sold today as Molex’s KK connector. That connector is typically seen in a 4-pin configuration but is available with 2 to 24 pins, black or white housing, and polarization, and carries more current than 3-pin connectors (3-pin to Molex connector adapters are available). The housing and pins can be sold separately or as an assembly.

Many 3-pin connectors are inexpensive commercial products and widely available through online sellers. Higher-quality variations are also available from trusted distributors. and may come pre-assembled with a fan.

Design Notes

  • Voltage: 12 V
  • Current: 2 Amp
  • Materials: nylon, polyester, plastic
  • Temperature range: From -25 °C to 85 °C
  • Pins: The leads in a 3-pin connector are designated for power, signal, and ground. In a four-pin variant, the fourth lead is a control lead; in a fan application, it would control the speed of the fan.
  • Certifications: CSA, TUV, UL (94V-40 for flammability)
  • These connectors are often available in low halogen or halogen-free versions, especially in those used in appliances.

Markets, Sectors, and Applications

  • Consumer electronics (white and brown goods), computer equipment


Allied Electronics, Digi-Key Electronics, Newark, TE Connectivity

Related products:

  • Wire-to-Board Connectors

Like this article? Check out our other Meet the Connector and our Sensors and Antennas Page, and our 2022 Article Archive

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Amy Goetzman
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