PWM Vs DC Fan Noise

When you think about a computer’s fans, you’re probably wondering whether PWM or DC fans are quieter. Neither type of fan is completely silent, but you can reduce the noise they create by adjusting the speed or adjusting the tach cycle. PWM fans also use pulses with varying widths to regulate their operation. This type of control uses high frequencies and intermittent voltages to define the fan’s power cycles, the ratio of “powered” to “unpowered” within one cycle.

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Keeping the fan on long enough to get a complete tach cycle

Keeping fan on long enough to get tach cycle information from your computer is possible when you have a fan controller that implements the tach cycle feature. Analog Devices’ fan controllers include the ADM1031, ADT7460, and ADT7471. This feature has a disadvantage, however: the audible noise can increase, which is why you should avoid this method if possible.

Adjusting fan speed to reduce acoustic noise

You can also try a different setting, such as varying the fan speed. This way, you can avoid having annoying noises. Some people even use variable speed muffin fans. A variable fan speed will help reduce the noise from the computer’s fans. But remember to avoid the extreme setting, as it will increase the computer’s power consumption. Moreover, you’ll need to make sure that the fan is always on, so it won’t run out of electricity.

Another method of reducing fan blade noise is to install an active noise cancellation device. This noise canceling device will receive audio signals generated by rotating fan blades and will emit sound waves of equal phase and amplitude. The device is located near the fan and symmetrically aligned. The number of speakers will correspond to the number of blades, and the position of the array will be adjusted until maximum destructive interference occurs. A phase shifter is also used to provide noise cancellation for variable speed fans.

Pulse width modulated (PWM) fans are quieter

PWM or pulse width modulated fans are quieter than DC fans. They use a 4-pin signal instead of two and function based on a pulsating input signal. The voltage is lower than 12V, and DC fans are noisier when they’re running. However, the difference in noise is mostly in the RPM. Both types of fans have the same purpose: to cool the computer. They also provide the same amount of cooling but control them differently.

PWM control works by regulating the amount of power fed to the fan. When the fan is running in PWM mode, its voltage is not varying. Instead, it has upticks to maintain a constant speed that corresponds to the system’s demand for cooling. This means that the fan is operating at a low speed of 10% of the time, reducing power consumption. PWM fans have higher duty cycles than DC fans and can achieve lower speeds while reducing power consumption. Some premium PWM fans use a patented analog circuit to smooth the square signals that are generated by the fan’s motor.

DC fans are louder

Both DC and PWM fans are effective in cooling your computer, but DC fans are noisier, and their low-voltage operation causes electrical noise. PWM fans, on the other hand, run at a constant 12V, and their noise level is lower when they’re idle. While they’re more expensive than DC fans, they use less power and produce less noise. In addition, PWM fans can also function with a lower duty cycle, which reduces their noise during idle periods.

One of the most common concerns about DC ceiling fans is their noise. Fortunately, DC fans can be controlled with software that makes it easy to choose the optimal speed and voltage. These fans use a three-wire connection that has a tach output (a signal related to the fan’s speed). In general, DC fans are louder than PWM fans, and they run at maximum RPM regardless of the perceived temperature.