You need to change BIOS settings in the Fan Control section.
Just click the temperature and find RPM settings.
The point is, that you have to adjust Target temperature, the default is 85 degrees, I guess.
So, you change target temp to for example 50 degrees, and the range of CPU cooler RPM %.
Target temp means motherboard tries to maintain set (50 degrees) temperature of CPU or lower.
The default setting of 85 degrees means, that CPU RPM will raise only when CPU temp reaches that value, which I have never seen. That is why your RPMs stay around 1000.
Minimum is set to 20% and max to 100%. Also, you should enter degree at which RPM go to 100% (for example 75 degrees).
It is not some issue with hardware itself, it is just settings, that need to be changed.
Hope that helped.
Amazing, thank you.
I had given up on trying to find this solution, I had tried everything I could think of in the fan settings, but it never occurred to me that it was the temperature settings I needed to adjust.
My CPU fan now varies as I had intended when I built my computer, thank you.