When you are working on a laptop, you might observe variations in the heat produced. This variation in heat dissipation often leads to questions on cooling fans and their speed. When the laptop’s heat is less, there is not much need to run the fan at full speed. However, if the laptop is extremely hot, the computer might even need additional fans. The speed control of cooling fans is a much-debated topic and PWM fans and DC fans are the most frequently discussed solutions. DC Fans or 3-Pin Fans Once installed, it monitors your system’s main sensors. This includes voltages, temperatures, and fan speeds. It also reads your drive’s S.M.A.R.T. vital stats and even keeps a watchful eye over your video card. There are PWM controllers and there are PWM fans, but the way in which PWM is implemented in each differs greatly: a standard PWM controller modulates the 12 V supply line of an “ordinary” 12 VDC motor. Conversely a PWM controller for PWM fans – such as the one featured in this article – doesn’t modulate the 12V supply line but instead sends a PWM signal along a different supply line (the magic “fourth wire”) to a more advanced 12 VDC motor, leaving the 12 V supply line uninterrupted. Designated PWM fans not only have internal circuitry which differs from that of standard fans but because they are designed with speed control in mind the motors themselves are usually more advanced (and expensive). So, PWM speed control of a standard fan is indeed very different from PWM speed control of a PWM fan… Nidec even goes so far as to say that modulating the main supply voltage is not advisable:

Fan Controller for PWM Fans - Overclockers DIY Fan Controller for PWM Fans - Overclockers

Plan your circuit on a piece of paper, familiarizing yourself with each component (learn what it looks like and what it does) and the layout of the circuit, and taking time to arrange it in such a way that it is clean and clear. Think of a PWM signal as if it were a beating heart. Rather than being powered by a continuous supply of power (which would ordinarily be the case) our DC fan motor is being fed with pulses of power; it is essentially being switched on and off very rapidly. These on-off pulses are delivered to the motor several thousand times per second, and because the intensity (or width) of each pulse can be changed, so the speed at which the motor turns can be changed. The image below shows how different pulse widths affect the resulting power of the PWM signal: Three different PWM signals showing average voltage PWM Controllers vs. PWM Fans https://github.com/Mourdraug/FanControl.AsusWMI to interface with ASUS motherboards through WMI methods The same efficiency rule that applies to resistors also applies to transistors— Their resistance results in wasted energy because they burn off some of it as heat. They act like heaters in that regard.

Introduction

Timer 0 (Pins 5,6) is identical to Timer 2, so we could apply the same settings that we used for it and get an extra output for a fourth fan; however, it is used for all timing functions such as delay, millis, etc. and touching it would cause everything that depends on this to behave erratically, including our Serial output. My code doesn't touch this timer. First and foremost, make sure you take your time if you decide to build this (or any other) circuit for use with your system – working with electricity is hazardous (and if not for you, certainly for your hardware!) so be careful. I’ve shorted my PC (yes, my entire system) no fewer than FOUR TIMES since I started messing around with DIY fan controllers, and unfortunately one of these shorts fried my prized Foxconn X58 motherboard. Suffice to say, I have been more cautious since.

Fan Controllers of 2023 – Internal and External - PC Guide Best Fan Controllers of 2023 – Internal and External - PC Guide

And remember: This circuit uses 5v, NOT 12v. Step 5: Debugging Digital Multimeter – a must for testing circuits and componentsThe controller also comes with a fan speed remote but since it comes with only three speed presets, it’s better to connect the controller to a PWM fan header on the motherboard since you cannot use both at the same time.