Noisy CPU fan

[Tilltech]

I set the CPU fan in BIOS on automatic - level 9 - to run when CPU temp gets to 55C.

However, the CPU runs almost all the time at a temp lower than 35C, but the fan is always at max level, which creates a lot of unnecessary noise.
How can I fix this?

[quest_for_silence]

Start from your complete specs.

[Tilltech]

MBO - Asrock 980DE3U3S3 R2.0
CPU - AMD FX 6350 3.9GHz
CPU cooler - SCYTHE Big Shuriken 2 Rev. B
CASE - Zalman Z3

[quest_for_silence]

On ASRock boards the target fan speed is the minimum speed a fan connected to the CPU_FAN header will operate at.

That's because any fan starts at different minimum speed, that is different voltage (or duty cycle, for PWM fans): therefore you can set the Level settings, from 1 to 9, which allows you to select the minimum speed the fan will operate at, in order to comply to those different starting voltages (or duty cycle, for PWM fans).

So, choosing the Level 9 you basically told to your CPU_FAN header to start at highest (noisiest) fan speed (I don't know how much it is, but it's the highest) and to mantain that speed until the target CPU Temperature threshold were hit, and then automatically increase the fan speed to 100%. Instead, to lower the overall noise, you should have done the opposite.

BTW, that BIOS is fairly basic: probably SpeedFan won't work on your board, but there should be an ASRock utility to control the fans inside the OS, check it out at least.

[Tilltech]

Yes, I tried to install Asrock OC tuner, none of the versions work with Windows 10.

So, if I set the speed to 6, it will still ramp up to 9 if the threshold gets to 55C?

[quest_for_silence]

Yes, I tried to install Asrock OC tuner, none of the versions work with Windows 10.

Then give a read to the SPCR guide to SpeedFan and try whether it works or not.

So, if I set the speed to 6, it will still ramp up to 9 if the threshold gets to 55C?

Jeez...

...no, you miss the point: the speed level is only the minimum speed, while the maximum speed is always 100% of the fan speed (so no speed level is representative of it): you can't modify the maximum speed and also the slope, I mean how fast the fan rises from the set speed level to that 100%.

So that, if the speed level were set to 1, if/when the temp threshold were hit, the BIOS will automatically increase the speed from level 1 (unknown % of the rated fan speed, I guess it could be like 10%) up to 100%; and if it were set to 4 (I guess it could be like 40% of the rated speed), if/when the threshold were hit, the BIOS will automatically increase the speed from level 4 (so, supposedly 40% of the rated fan speed) up to to 100%; or, if it were set to 6 as you would want to do (I guess it could be like 60% of the rated speed), if/when the temp threshold were hit, the BIOS will automatically increase the speed from level 6 (so, supposedly 60% of the rated fan speed) up to to 100%; and if it were set to 9 like in your current case (I guess it could be something like 90% of the rated speed), if/when the temp threshold were hit, the BIOS will automatically increase the speed from level 6 (so, supposedly already the 90% of the rated fan speed) up to to 100%; and so on.

Eventually you can't go from "level 6" to "level 9", but from "level 6" to 100%, accordingly to an automatic and unknown pre-set fan curve.
Summarizing, if you work just with the BIOS fan settings, you have to found on a trials basis "your" minimum speed, i.e. the speed level, using some stressing tool (such as Prime95), in order to set it to the lowest level which is at the same time: a) comfortable to your ears; b) and safe for your temps (if you set it too low, probably you will hit the threshold too much quickly, and the system will rather often become noisy; if you set it too high, as it is now, you will always get more noise than necessary).

Take also note that 55°C is likely way too low as a threshold, you may end up revving the fan up and down indefinitely on tough conditions and at any rate having an unnecessarily noisy rig (albeit I know that looking for the correct threshold would be somewhat difficult without a fan controller, either hardware or software like Speedfan).