What is the point of PWM Fans and do I need them?

[Bob Jim]

Title is my query. I will probably be using be quiet!s fans, just wandering whether or not I need PWM and what difference it makes.

[Godlygamer23]

PWM allows you to have more precise control over your fan speeds - instead of running at a set voltage like +12V, +5V, and +7V, PWM allows the fan to technically run at +12V but sends out pulses of it. When reducing the fan speed, it simply sends less pulses allowing for more precise control.

[zyntaxable]

If you're using a fan from be quiet you won't need PWM, because they're so silent you won't hear them very much at all when they're running at full power.

[ImBleu]

As for the difference between 3pin ( Volt regulated ) and PWM ( Pulse-width Modulation ) in the real world is essentially nothing. The main difference is the smoother speed-up and speed-downs so that the change is not as noticable, slightly better with cooling as well.

If you want to go in depth on PWM; https://en.wikipedia...idth_modulation

 

 

But it's nicely summed up by other above me as well

[Daniel123dk]

If you're using a fan from be quiet you won't need PWM, because they're so silent you won't hear them very much at all when they're running at full power.

that is not quite true. If he runs a non pwm bequiet fan, then it runs at 12v (full speed) and that is loud (i am owner of 6 silent wings 2 pwm's) 

 

i would totally go for pwm over a standart one.

[zyntaxable]

that is not quite true. If he runs a non pwm bequiet fan, then it runs at 12v (full speed) and that is loud (i am owner of 6 silent wings 2 pwm's) 

 

i would totally go for pwm over a standart one.

Hmm I have a bunch of non-pwm be quiet's and I barely hear them. I guess it has to do with the case one has as well

[Quinnbeast]

I use three voltage-control 3-pin (2x stock Fractal 140mm fans + 1 Phanteks) fans in conjunction with Asus FanXpert, and functionally, I have no need to change them to PWM. I get a control range of 450 to 1200 RPM, i.e. inaudible up to full speed. Also, it's just as much about what your motherboard supports rather than which is 'better'. I'm on a z77 chipset (Ivy Bridge), and only the CPU header is genuine PWM in this instance, the rest are voltage control.

 

Most fans are only inaudible once you get down towards 500RPM or slightly lower, but that will depend on other factors such as your case, any other system noise, how quiet the room is and how much the fan noise actually bothers you. Even a low-RPM fan (Noctua Redux 900 or Be Quite 1000RPM) would really bug me at full speed, but PWM is not automatically preferable to controlling fan speed.