Commonly used cooling fan voltage is usually 12V, but like temperature-controlled cooling fan, the voltage setting for cooling fan is relatively low at low temperature, resulting in slower speed and lower noise of cooling fan.

As long as the cooling fan can operate normally under low voltage and start smoothly, there is no problem that the voltage is lower than 12V. If the 12V cooling fan with high speed can operate as low as 5V or even 4.5V, the sound will be quieter.

However, the 12V cooling fan can't be applied to be more than 10% of its rated voltage, such as 13.2V operation, so it is likely to exceed the power and cause the cooling fan to burn out, especially for some cooling fans with high air volume and high rotating speed, if it is possible to be more than the rated voltage, it is necessary for the supplier of the cooling fan to increase the voltage range.