3-pin cooling systems

3-pin

— an outdated, but still quite popular connector, widely used in active cooling systems. The key difference from the 4-pin connector is that this type of power supply does not allow the use of automatic speed control using PWM technology, although a simpler thermocouple-based control is available for it (for more details, see "Additional — auto speed control"). Otherwise, these connectors are completely similar — to the point that many motherboards allow you to turn on a 3-pin cooler to a 4-pin power output. However, this possibility should be specified separately; and in some components (for example, video cards) it is not available at all.