DC vs. PWM Fans: Which Is More Effective at Cooling Your Computer?

While computers create considerable heat, excessive heat can damage the internal components of your computer. Fans are a critical component of your PC since they help to dissipate this heat and keep your computer steady.

If you’ve ever built a computer or delved into the BIOS, you’re likely to have come across the terms DC and PWM – the two basic types of fans found in a computer. What are they, then? We’ll examine the distinctions and determine which fan is the best fit for your needs.

What are direct current (DC) and pulse width modulation (PWM) fans?

The two primary types of fans seen in computers are direct current (DC) and pulse width modulation (PWM). These fans are fundamentally different in ways that affect how you utilise them on a computer.

What does it mean to be a DC fan?

A direct current fan is a type of computer fan. They operate at a constant voltage supplied by a direct current power supply or the motherboard and provide continuous cooling for your computer.

DC fans are equipped with a three-pin connector consisting of a power supply pin, a ground pin, and a signal pin. The signal pin collects information about the fan’s speed (referred to as the tachometer output) and notifies the user if the fan stops working.

Although 12V is the most common voltage for DC fans, they are also available in 5V, 24V, and 48V. The higher the voltage, the faster the fan spins and the more cooling occurs. This means that you can reduce the speed of the fan by lowering the voltage, albeit most fans will stall at a certain rate.

Certain DC fans now include an integrated voltage controller, while it is also possible to adjust the voltage via the BIOS or a third-party fan controller.

What is a Pulse Width Modulation (PWM) Fan?
PWM fans are quite similar to DC fans but have an important distinction: they contain an additional pin for pulse width modulation. This fourth pin receives data from the motherboard and is used to control the fan’s speed directly.

PWM fans operate on the basis of repeated pulses of power. In essence, PWM fans are either ON or OFF and can be swiftly cycled between the two states to control the overall fan speed. A duty cycle is the term used to describe this pulsating. A 40% duty cycle, for example, means that the fan runs for 40% of the time over an entire cycle.

The motherboard regulates the speed of PWM fans based on temperature readings from various components of the computer, most notably the CPU. Additionally, due to the way PWM fans are operated, they can operate at significantly lower speeds than DC fans.

Significant Differences Between DC and PWM Fans
Despite their similarities, DC and PWM fans may be better suited to various applications due to their variances. Bear in mind, however, that there are numerous additional factors to consider while determining the finest case fan for you.

Related: How to Choose the Best Custom PC Case Fans

Pins
DC fans are entitled to three pins:

Pin 12V power supply
Tachometer grounding pin
PWM fans are equipped with four pins:

Pin 12V power supply
Tachometer grounding pin
PWM jack
Control of Fan Speed
The speed of a DC fan can be adjusted by restricting the voltage provided to the pin. In comparison, PWM fan speed is controlled by precisely switching on and off the fan motor during duty cycles. While DC speed control is not as sophisticated as PWM, this does not detract significantly from its effectiveness, especially in newer versions.

In essence, you have significantly more control over PWM fan speed, however DC fans with control knobs are becoming more prevalent.

Fan Speed Requirement
Due to the fact that the DC fan’s speed is reduced by lowering its voltage, it can stall below a particular voltage threshold. This occurs when there is insufficient power to keep the fan spinning. By lowering the duty cycle on PWM fans, you can get a significantly lower fan speed.

Additionally, PWM fans will never stall, as their entire function is repetitively turned on and off.

Noise
As a result of the increased speed control provided by PWM fans, even when the computer does not require additional cooling, the fan will spin much slower and make significantly less noise than DC fans. Due to the fact that DC fans often run faster than PWM fans when idle, they are noisier.

Additionally, keep in mind that some DC versions will emit electrical noise (one of those peculiar PC noises that occasionally occurs) while not functioning at 12V. This is not an issue because PWM fans always operate at 12V.

However, during peak PC performance, differences in noise levels will be negligible. The primary factor affecting noise is the fan’s maximum RPM and general build quality.

Cost
DC fans are typically less expensive than their PWM counterparts due to their lower manufacturing costs. Thus, if pricing is your primary consideration, DC is unquestionably the superior option.

Consumption of Electricity
Due to the way PWM fans operate, they are generally more efficient and consume less power than DC fans. Take a look at the duty cycles of PWM fans. When a fan operates at a 40% duty cycle, it consumes electrical power just 40% of the time. By comparison, DC fans will operate at a somewhat lower voltage.

Principal Applications
DC fans are more frequently utilised as case fans or in instances where the system would likely require constant fan speed, such as a 24/7 server. PWM fans are more advantageous if noise is an issue or if you want to maximise the efficiency of your system.

Which Fan Is the Superior?
Over time, technology has advanced to the point that there are few reasons to prefer one over another.

PWM fans are typically more expensive yet consume less energy and make less noise. DC fans are likely to be equally effective and less expensive, but they will be noisy.

Consider the quantity of 4-pin connectors on your motherboard. If you have a lot, you can consider stocking up on PWM fans, which are slightly more effective. However, if you’re in the market for case fans (and noise is not an issue), there’s no reason not to opt for the less expensive DC fans.