BIOS Fan Control not working

rai523

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May 24, 2012
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Hello there, I just want to ask for your help regarding my problem on my motherboard EVGA X58 Classified 141-BL-E760-A1, the BIOS fan control is not working, I tried using smart fan and manual already and, still my fans are always at 100%, I already updated the bios to the latest version already and still it doesn't work.
 
Solution
It's designed to provide fan control for PWM fans that have 4 pins.

A 3pin fan has connectors for power, common (ground), and RPM reporting (tachometer). Many, if not most, newer mobos can control these fans by adjusting the voltage level fed to the fans based on the RPM reading it gets from the fan. I.e. 12V gets 100% of the fan's max rated RPMs, 9V gets @ 50%, etc.

A 4pin fan only gets one voltage level - 12V. The speed of the fan is controlled by pulse width modulation (PWM), which basically means the fan gets a signal through the 4th pin to turn on and off rapidly at a rate calculated to result in a specific RPM.

Some mobos have PWM fan headers that you can switch the mode on from PWM control to voltage control. If the...

rai523

Honorable
May 24, 2012
25
0
10,530


my fans are only 3pin but in my other computer which is newer they have the same fans but i can control them even they are 3pin only,the fans are corsair sp120s
 

rai523

Honorable
May 24, 2012
25
0
10,530


it's not working, i don't understand the smart fan function of the motherboard, why did they put it, if the board doesn't support fan control?
 
It's designed to provide fan control for PWM fans that have 4 pins.

A 3pin fan has connectors for power, common (ground), and RPM reporting (tachometer). Many, if not most, newer mobos can control these fans by adjusting the voltage level fed to the fans based on the RPM reading it gets from the fan. I.e. 12V gets 100% of the fan's max rated RPMs, 9V gets @ 50%, etc.

A 4pin fan only gets one voltage level - 12V. The speed of the fan is controlled by pulse width modulation (PWM), which basically means the fan gets a signal through the 4th pin to turn on and off rapidly at a rate calculated to result in a specific RPM.

Some mobos have PWM fan headers that you can switch the mode on from PWM control to voltage control. If the header can't switch modes, the result is that if you plug a 3pin fan into it, the mobo/header can provide it 12V and monitor it's RPM, but it's also sending a PWM control signal that the fan isn't capable of receiving. All it knows is that it's getting 12V, so it runs at full speed.

If your mobo doesn't support voltage control, you have some options:
1. Connect your fans to an integrated manual fan controller if your case has one. If it doesn't you can install an aftermarket fan controller.
2. Get a step-down adapter - this will reduce the amount of constant voltage received by the fan (i.e. 9V, 7V). You still can't change the speed at will, but the constant RPM will be lower, as will the noise level.
3. Live with your fans at max all the time.
4. Replace your fans with PWM models.
5. Replace your mobo with one that does support voltage control.
 
Solution