PWM fans with a minimum speed of 0rpm?

[Mytrenet]

Hello, I have been wondering, is it possible to have a set of pwm case fans that are able to turn off completetly at 0rpm? just like gpu fans?

I mean, its nice to always have fans running at certain speeds, but what if the computer with its cooling solutions is able tu have no fans running at idle and mantain acceptable temps?

All I want to know is if its possible to do this, to be able to run the fans at 0rpm using a fan curve, and if so how ? I have tried on my motherboard from changing the fan curves with the asrock utiltiy to speedfan but it never works, setting any curve to 0% will just pump up the fans to 100% speed. Is there any piece of hardware that would help me do this ? or will I be only able to do this using 3 pin fans as my motherboard is able to regulate voltage on 3 pin fans which means fans can be turned off if they are 3 pin.

I know that there are temperature concerns but again, this is just to set up a fan curve that when the pc is idling at lowest temp, it brings teh fans down to a stop as to be silent completely and then ramp up the fans again if the computer goes above certain temperature.


Thanks for taking your time in answering or reading here.

 

[CountMike]

I doubt you could find any system that can stay cool and run at 0rpm CPU fan for any length of time. Disconnect yours and see how far that gets you to. Most modern MBs wouldn't even let you start it without it running.
Case fans are different story but it's bios that regulates their speed, fans only have a minimum voltage threshold for starting up, mostly 6 - 7.5 - 9v.
If BIOS can't do that, than you would have to use some separate fan controller.

 

[Mytrenet]

I doubt you could find any system that can stay cool and run at 0rpm CPU fan for any length of time. Disconnect yours and see how far that gets you to. Most modern MBs wouldn't even let you start it without it running.
Case fans are different story but it's bios that regulates their speed, fans only have a minimum voltage threshold for starting up, mostly 6 - 7.5 - 9v.
If BIOS can't do that, than you would have to use some separate fan controller.

I understand about the CPU Fan, but what about case fans? how come a gpu can stay with fans off?

And as I said, the idea is to set up a fan curve that will turn off the fans if any temp goes below certain temp as I live in a house with air conditioner at about 20C all the time, as long as the pc stays under 35 to 40C I would like my pc to have all fans turn off and then turn on with a fan curve.

What I want to know is if that is there any pwm fan that can go to 0rpm without trouble? or at least why setting a 0% value on any fan speed ( on the fan curve utility) will get my fans to run at 100% ?.

 

[CountMike]

GPU fan can stay off because it's BIOS lets it but even those fans have some startup value, about 1/4 - 1/3 of full RPM. Other than starting voltage, fans don't have much say in that matter, it's BIOS that commands them by voltage and frequency of pulses in case of PWM.

 

[madmatt30]

Arctic cooling tc range switch off completely below 30c (they have a temp sensor you can place where you like.

Their bionix range go rght down to 200rpm .

They make a passive fan that switches off below 50% pwm duty cycle, not sure however if you can buy them seperately asbthey come with the freezer 32/33 semi passive cpu cooler range.

 

[Mytrenet]

GPU fan can stay off because it's BIOS lets it but even those fans have some startup value, about 1/4 - 1/3 of full RPM. Other than starting voltage, fans don't have much say in that matter, it's BIOS that commands them by voltage and frequency of pulses in case of PWM.

Arctic cooling tc range switch off completely below 30c (they have a temp sensor you can place where you like.

Their bionix range go rght down to 200rpm .

They make a passive fan that switches off below 50% pwm duty cycle, not sure however if you can buy them seperately asbthey come with the freezer 32/33 semi passive cpu cooler range.

I just bought bionix fans half an hour ago, 4 fans, 3 140mm and 1 120mm ones. Those low rpms seem like the closest thing I can buy to have a near silent system.

And I know that the bios limits this things, but is it possible to run pwm fans off a fan controller hub which allows the user to turn off the fans when the computer is in low temperature?

 

[TJ Hooker]

Pretty sure it would depend on the fan controller. If the fan controller let you set 0% duty cycle for PWM, it doesn't matter what the fan was designed to do, it will completely stop. The only question then becomes what the minimum speed of the fan is. It's possible you'll need to jump from like 0 to 30% PWM in order to get the fan to turn on.

What is the lowest setting you can set on your motherboard fan curve that's above 0? What happens if you set it to 1% or something?

 

[Mytrenet]

Pretty sure it would depend on the fan controller. If the fan controller let you set 0% duty cycle for PWM, it doesn't matter what the fan was designed to do, it will completely stop. The only question then becomes what the minimum speed of the fan is. It's possible you'll need to jump from like 0 to 30% PWM in order to get the fan to turn on.

What is the lowest setting you can set on your motherboard fan curve that's above 0? What happens if you set it to 1% or something?

I bought the bionix fans and hooked them up 2 for each fan header, the results are actually nice. When the % is really low, I am assuming that 2 fans on one header means that the minimum voltage gets split if they are in parallel (somehwat basic knowledge of circuits) , but at 5% both fans for one header turn off completely, this fans are really good at they push a lot of air at low rpms and I can turn them off completely when room temp is below 24C and the pc does not go above 38C .

Setting fan curve at 0% for the bionix fans turns them off, for the cpu it puts it to max, and the older arctic fans I had would crank them up to 100% too. No idea what is the difference. Thanks for the help.