How to Wire a PC Fan

Written by david sandoval
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How to Wire a PC Fan
(fan image by dr0p from

As computer systems become faster, the electronic components housed within a computer case require more electrical power. Much of the electrical power drawn by computer components is converted into waste heat.

One way of managing heat dissipation within a computer case is by adding a PC fan. Many PC fans plug directly into the computer motherboard. However, if you must place a fan in an area that is not easily served by a motherboard fan power port, you may choose to wire a PC fan to work with one of the disk drive power cables.

Skill level:
Moderately Challenging

Things you need

  • Four-circuit (single row) female Molex connector
  • Two Molex socket crimp terminals
  • Direct-current, 12V fan
  • Electrical pliers

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  1. 1

    Strip 1/2 inch of insulation from each of the fan electrical leads. Insert the red wire into one of the crimp terminals, and crimp the wire to the terminal. Insert the black wire into the remaining crimp terminal, and crimp the wire to the terminal.

  2. 2

    Insert the red fan wire through the rear end of the first pin position on the Molex connector. Push the wire into the hole until the crimp terminal snaps into place. Insert the black fan wire into the second pin position, and push the wire into the hole until the crimp terminal snaps into place.

    How to Wire a PC Fan
    Pin 1 on the Molex connector pictured here is the bottom pin. (medusa colour image by robert mobley from
  3. 3

    Plug the Molex connector into one of the unoccupied PC power connectors inside the computer.

Tips and warnings

  • If the pins are inadvertently reversed, the fan will run backward. This may still move air away from the computer component, depending upon fan placement.

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