My fan wont go lower than 900rpm

[ibrahim1234]

Hello

I just bought a Noctua nf-a14 PWM 140mm and its running at around 900rpm and its kinda noise when im just surfing the internet.. i tried the software called "SpeedFan" and saw some tutorials on youtube but i just cant lower it to around 500-600 (lower than that if possible). Anyone have some suggestion on how to do it? ill post some pictures to illustrate my problem if its any help.

 

[Nick_50]

It can go down to 300rpm, what motherboard do you have? Does it have any fan control built into the bios?