Motherboard voltage control insted of pwm

[Lakiza]

Hi, I'm having a problem with my aftermarket cpu cooler fan. It is a pwm controlled (4 pin) 120mm fan. I plugged it in the cpu fan header on the motherboard. It works fine on 0% and 100%, but other than that it squeals. The problem here is that the motherboard is not controlling it with pwm, it is controlled by voltage. This pwm fan is designed to work on 12V, anything below that will cause it to squeal.

I have tried plugging a 3pin (no pwm) fan in this header and changing the speed does affect the fan, meaning that it's the voltage changing. Or maybe the motherboard is sending modulated 12V instead just sending a pwm signal to the 4th pin and letting the fan do its thing.

This makes the 4th pin on the header useless. Is there any way to change the operating method of the fan header Voltage/Pwm? I have asked Gigabyte btw, i'm just asking if you have any ideas to fix this.

I have checked the BIOS and there isn't any option for this, although setting the control to manual does mention pwm, however it still affects the 3 pin fans so it isn't actually pwm controlled. My motherboard is a Gigabyte F2A68HM-S1. I have had this issue with my previous motherboard, an Asus M2N68 Plus, and solved it by setting the fan to default in bios, and altering the speeds via SpeedFan.

 

[cin19]

I read from the manual, if you set the "CPU Fan Speed Control" to "normal", and the fan will run at different speeds according to the system temperature. You can adjust the fan speed with EasyTune based on your system requirements. Just using the EasyTune, maybe speed fan does not work on your MB.
Manual (page 21) http://download.gigabyte.us/FileList/Manual/mb_manual_ga-f2a68hm-s1_e.pdf

 

[Lakiza]

I read from the manual, if you set the "CPU Fan Speed Control" to "normal", and the fan will run at different speeds according to the system temperature. You can adjust the fan speed with EasyTune based on your system requirements. Just using the EasyTune, maybe speed fan does not work on your MB.
Manual (page 21) http://download.gigabyte.us/FileList/Manual/mb_manual_ga-f2a68hm-s1_e.pdf

I did try that, but as i said, it still changes the voltage and the fan squeals. I have tried both SpeedFan and EasyTune6, but it still is changing the voltage instead pwm when i change the speed. A 3pin fan you should not be able to control with pwm since it only has 12V - Ground - Sense, i played with the sliders and it did affect the 3pin fans. Something is very wrong here. I've read that on some motherboards there are 4 pin fan headers that aren't pwm, they control voltage on 12V rail and have a constant 5V on the pwm pin to make the transistors in the fan constantly active. I really hope that this is not the case.

 

[cin19]

The MB has the 4-pin cpu_fan header, you may e-mail or call gigabyte to find out it does control by voltage or not, I really hope that this is not the case too, usually we know the 4-pin is for pwm. Also you may add the link you find the 4-pin fan header isn't pwm when you e-mail gigabyte.