All Discussions > Steam Forums > Hardware and Operating Systems > Topic Details
Prowlcorp Mar 30, 2016 @ 1:03pm
DC vs pwm
Ok so I have an option in BIOS where it's on DC which means the lowest it runs is 50% and pwm meaning it can go lower at lower temp. Should I leave all at DC or switch case fans to pwm? I tried clicking pwm on case fan 1 but it suddenly revved up fast despite low temp
< >
Showing 1-7 of 7 comments
_I_ Mar 30, 2016 @ 4:11pm 
if the fan has 2 or 3 wires use dc
if its 4 wire fan, use pwm
#1
Azza ☠ Mar 30, 2016 @ 4:17pm 
PWM means pulse width modulation. PWM is when you pulse a DC voltage off and on. The pulses are going so fast that they do not turn the fan off and on.

Rather it lets the motherboard or a fan controller adjust it's speed.

PWM is more efficient, rather than voltage regulator (which just waste energy as heat output). PWM is also more accurate and controlled digitally, it requires a controller to work, which it can automatically adjust the fans RPM's depending on the temperature.
Last edited by Azza ☠; Mar 30, 2016 @ 4:19pm
#2
Prowlcorp Mar 30, 2016 @ 4:52pm 
ok. So my last MB was able to control my 3 pin fans by default but this one won't shut it off at low temp.
#3
_I_ Mar 30, 2016 @ 5:30pm 
change the pwm settings in bios, should have config options for it
#4
Azza ☠ Mar 30, 2016 @ 7:05pm 
Originally posted by Prowlcorp:
ok. So my last MB was able to control my 3 pin fans by default but this one won't shut it off at low temp.

If your motherboard only has 3-pin, the 4th pin which is the sensor is left out (which lets it detect temperatures and lower the speed). PWM will still run the fan, but not control/adjust it's speed automatically. It will most likely just run at full blast.

You basically are better off on DC in that case.
Last edited by Azza ☠; Mar 30, 2016 @ 7:06pm
#5
Prowlcorp Mar 30, 2016 @ 8:56pm 
well the last and this MB are both 4 pin headers but my fans are 3 pin
#6
Azza ☠ Mar 30, 2016 @ 9:18pm 
Originally posted by Prowlcorp:
well the last and this MB are both 4 pin headers but my fans are 3 pin

Yeah, your motherboard might support PWM, but those fans aren't PWM.

I personally use 140mm premium Noctua fans, such as NF-A14. These will have PWM labeled on the box and has 4-pin PWM cable (also L.N.A - Low noise adapter). Making the Noctua branded fans one of the most quietest fans available (but also more expensive).

I suggest if your fans are fine, just leave it as is... disable PWM.

If you do want to replace them however and make use of PWM, then consider Noctua fans or similar.

Note: Larger the fan, the better - it gives more airflow, with less effort and therefore less noise. If you have 120mm fan screw holes on the case, consider rounded 140mm (with 120mm fitting) fans, if they can fit. Get rid of any fan smaller than 120mm.
Last edited by Azza ☠; Mar 30, 2016 @ 9:21pm
#7
< >
Showing 1-7 of 7 comments
Per page: 1530 50

All Discussions > Steam Forums > Hardware and Operating Systems > Topic Details
Date Posted: Mar 30, 2016 @ 1:03pm
Posts: 7
Start a New Discussion

Discussions Rules and Guidelines