Case fans

[Villakid86]

Sorry for the stupid question but should i get pwm or dc fans i dont know the diffrence 

[ki8aras]

8 minutes ago, Villakid86 said:

Sorry for the stupid question but should i get pwm or dc fans i dont know the diffrence 

pwm=better control

dc=cheaper

[boggy77]

for pwm you can set fan curves based on temperature.

for dc, you just set a fixed voltage that means a fixed fan frequency

[DJ46]

PWM fans are easier to control as stock heatsinks from both CPU manufacturers use PWM fans so every single motherboard has to have at least one PWM header.

If you only have this header and a case full of fans, you can still control them - the PWM signal doesn't use much power and can be split between a ton of fans that are controlled by the motherboard but powered straight from the PSU.

 

DC speed control exists, don'ts let anyone tell you otherwise. It can be a lot harder to use though. One of the things you have to look out for is the fact that while a lot of fans can run at as little as 5V (some can even go below 4V), most need at least 7V to start turning. A PWM fan doesn't need to be "kickstarted" at higher RPM, it will just start spinning once the fan speed is set high enough, since it has 12V going to it all the time and the signal tells it how fast it should spin.

 

You have to check your motherboard manual and often also look at the experience of others with the same motherboard - these days, all headers on motherboards are 4pin, but often the 4th pin that is supposed to control PWM fans isn't actually connected to anything. This can also tell you whether the DC fan control is any good.

 

An example (my motherboard):

Spoiler

On my motherboard there are 2 fan headers: a CPU fan header and a single system fan header.

The CPU fan header supports PWM but doesn't support DC speed control. This at one point led to me returning a 3pin fan because I thought it would run at full speed all the time.

The system fan header supports both PWM and DC speed control. To control DC (3pin) fans, I use SpeedFan because my motherboard didn't let me select voltage control. SpeedFan doesn't work on newer motherboards, but those usually just have a BIOS setting that lets you choose between PWM and DC speed control.

 

[DJ46]

46 minutes ago, boggy77 said:

for dc, you just set a fixed voltage that means a fixed fan frequency

Huh, my 3pin DC Noctua NF-P12 controlled by a fan curve based on temperature suddenly popped out of existence when I read this...