Question AISuite vs BIOS for Fan Control

[Mattaton]

I recently uninstalled AISuite, which I used exclusively for fan speed control via Fan Xpert. It allowed me to make my 3-pin fans much quieter than what I'm getting now that I am using BIOS alone. In the BIOS, the lowest I can go is 60% fan speed. If I switch to PWM mode from DC mode, some of the fans will go full speed, so I know PWM mode isn't the answer. How was AISuite able to do it, but BIOS can't? I'm running the latest BIOS for my ASUS Sabertooth X99.

What do you guys use to control 3-pin fans?

Thanks!

 

[shknawe]

Dosnt it allow you to make manual entry in fan control in bios? qfan?

 

[Mattaton]

Yeah, it does, but it won't allow me to move the bar below 60%.
FanXpert had my idle speeds around 500-600rpm, QFan is hitting 950-1000rpm at idle.

 

[Mattaton]

Old forum post, but same thing I'm dealing with.
https://rog.asus.com/forum/showthread.php?87161-Setting-Chassis-Fan-Control-below-60

I guess I needed to run the fan tuning under Monitor in the UEFI first so it could detect low end speeds, but it only does it for Chassis Fans and not Assist Fans. So, I can get the Chassis Fans down to 30% speeds now. Looks like I need to go buy some fan header splitters!!!

 

[Karadjgne]

It's the difference in the fans. 3pin fans are analog, the rpm is directly related to voltage. Max speed being 12v, minimum speed on good fans is 5v. Most mediocre case fans need 7v to start the blades moving. 12v = 100%, 5v=40%, 7v=60%. Since bios really can't differentiate exactly what a 3pin fan needs, it defaults to a safe minimum voltage, 7v which is 60% duty cycle.

4pin PWM is the opposite. It's a constant 12v. So if setting a 3pin fan on a pwm header, that fan gets a constant 12v. With pwm, the 4th wire is the pwm signal wire. Tells the fan motor on/off. So unless a pwm fan is at 100%, anything less is a constant state of trying to start. On-off-on-off. The longer the 'on' state, the faster the fan spins. This means pwm fans can go a lot lower duty cycle, good fans getting under 20%.

The motherboard will dictate exactly what each header can do, some work either pwm or analog, cpu_fan is dedicated pwm, cpu_pump is mostly analog, cpu_aux can be non controllable or pwm etc. Some bios allow either analog or pwm for sys_fan, some need setting 1 way or the other, either all pwm or all analog. It varies depending on the vendor and mobo.

 

[Mattaton]

Thanks. Yeah, I knew the basic difference between PWM and DC fans. Just didn't understand why Fan Xpert could do things the BIOS couldn't.
I'm closer now, but the ASST fans won't go below 60% even though they could with FanXpert. All the fans are the same model and I was able to set them all the same in FanXpert. The CHA fans are down to 30%. Which is fine.
I ordered some splitters so I can put all fans on the 4 CHA headers... Other than the CPU fan, obviously.