I have set the 'Silent' profile from BIOS, RPM is around 1400 and CPU temp is 30C, but the fan still make like a whirling sound, like a sudden change in the RPM even there is not such a change. I have set also the temperature interval to 3 degrees. The fan is significantly louder than all the other fans, I hear it even when the case is closed and without any system load. Do you think the fan could be damaged? Thanks!
I have found a potential fix for this. In BIOS you can select the type of the fan from AUTO, PWM and Voltage. AUTO and PWM are recommended for the 4-pin fan, but these settings run the fan at 1400 RPM which is very loud. If I select Voltage, the RPM drops to around 600 which is much quieter. Also the CPU seems to stay at around 35-40 degrees so there is no problem regarding the cooling. Maybe this will help others.
This makes a positive difference, but how do i know the processor is not overheating or just below overheating? Why are these 2 settings available, PWM and VOLTAGE, whats the difference and what is it used for?
Both PWM and Voltage modes can adjust the fan speed based on the CPU temperature. The PWM which is used for the 4-pin type fans is keeping a constant voltage and adjusts the fan speed using the 4th pin, which is the PWM control signal. The Voltage type adjusts the supply voltage of the fan and by doing this it changes also the rotational speed. With PWM you can have a finer control over the RPM while the voltage is a more rough control. You can monitor your CPU temperature either in BIOS or in various programs. You don't have to keep it at 30 deg C, you will be perfectly fine even with the CPU at 50 deg. The fans have a pretty good air flow even at 600 RPM, so you don't need them on max to cool the CPU. I have left the CPU fan on voltage control (even if it has 4 pins) and set the Silent profile in BIOS. I have no problem until now, the CPU is staying well below 50 deg. C.