The point of this guide is to show the latest and greatest in fan control technology on Intel Z270 motherboards and to help you understand what each brand has to offer in their high-end products. I will start with a primer on the differences between PWM and voltage mode technology and then go into the current offerings from almost all the vendors.
PWM vs. Voltage
So, how do you control a motor? Just like other electric devices, you feed it power and then it does something, and usually, you use a type of power supply regulator. In this case, the difference between PWM and voltage mode fans and headers is where this regulator is located. PWM fans have control circuitry built into the fan while voltage mode fans rely on the motherboard to regulate its voltage.
PWM Mode (4-pin fans): Stands for pulse width modulation, and it basically means you get pulses (basically going to an ON position) at a periodic rate, and in this case, it's thousands of times a second. These pulses result in a duty cycle, which can be used to calculate final voltage. So let's say in a 10-second cycle we pulse five times to 100% for one second each time. That would result in a 50% duty cycle since you are pulsing (turning on) half the time. If you feed a fan 12v constant and use a 50% duty cycle PWM rate, then you would theoretically get 6V.
So, PWM is a method to regulate the fan. PWM control is also used in your VRM and throughout your motherboard in many different places. In PWM mode the fan is fed 12v constantly, and then a PWM signal is sent up the fourth pin to the fan to control it. You should stay away from putting too many PWM fans on one header as they constantly pull 12v, I would instead get one of the splitters that expands the 4th pin to many fans and gets 12v directly from the computer's power supply. One of the benefits of PWM mode is that you can use one of these splitters and not strain the motherboard's fan header.
Voltage Mode (3-pin fans):Voltage mode is where the motherboard uses some type of voltage regulator to regulate the 12v wire going to the fan. Voltage mode has changed a bit over the years, where in the past it might have been linear regulators altering the 12v line, it's now possible to find a buck converter used to regulate the 12v line. It would switch on and off much like a PWM fan would to control voltage mode fans. Voltage mode headers don't have a fourth pin all the time, but they do control both PWM and voltage mode fans.
Why PWM? In general PWM fan control is more precise and offers a standard where vendors can custom design their own fan regulator for their fans, so the user gets the best experience. PWM control also wastes less power. PWM mode should also allow for a lower RPM than a voltage mode fan, and that is because the fan is being pulsed. Voltage mode uses a feedback mechanism, it will drive the voltage up to a certain level and then stop, but PWM is basically like calculating a set of bumps to get things going.
You can also alter the PWM slope and allow for much finer grain profiles. However, voltage mode fans are generally said to be as silent, and since they have been made for longer than PWM fans, they are usually cheaper, and you find them as stock fans included with cases. So you will inevitably come across a voltage mode fan. Most CPU fan coolers use PWM fans, as it's part of Intel's latest specifications.
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- Page 1 [Fan Types: PWM vs. Voltage]
- Page 2 [The Four Types of Fan Headers and a Test Fan]
- Page 3 [ASUS Z270 Fan Control]
- Page 4 [GIGABYTE Z270 Fan Control]
- Page 5 [MSI Z270 Fan Control]
- Page 6 [ASRock Z270 Fan Control]
- Page 7 [BIOSTAR Z270 Fan Control]
- Page 8 [Supermicro Z270 Fan Control and Final Thoughts]