The voltage requirements of DC computer fans are a critical aspect that must be carefully considered to ensure proper operation and compatibility within a computer system.

Most DC computer fans are designed to operate on a standard voltage, typically 12 volts (V). This 12 - V standard is widely used in computer systems because it is the voltage provided by the power supply unit (PSU) through the motherboard's fan headers. The 12 - V power supply is sufficient to drive the fan's motor at an appropriate speed to provide effective cooling. When a fan is connected to a 12 - V source, the motor spins, and the blades rotate to move air. If the voltage supplied is lower than the rated 12 V, the fan may not reach its optimal speed. For example, if a 12 - V fan is connected to a 9 - V source, it will rotate more slowly, resulting in reduced air flow and potentially inadequate cooling.

On the other hand, supplying a voltage higher than the rated 12 V can be extremely dangerous for the fan. It can cause the fan motor to overheat, leading to damage or even failure of the motor. In some cases, it may also cause the fan blades to spin at an excessive speed, which can create vibrations, noise, and eventually lead to mechanical failure.

There are also some specialty DC computer fans that may have different voltage requirements. For example, some low - power or small - form - factor fans may be designed to operate on 5 volts. These fans are often used in applications where space is limited or where a lower power consumption is desired, such as in some mini - ITX computer builds or in certain components with their own dedicated cooling solutions. When using such fans, it is essential to ensure that the power source provides the correct voltage. Connecting a 5 - V fan to a 12 - V source will likely destroy the fan, while connecting a 12 - V fan to a 5 - V source will result in poor performance.