I have had the problem for a few weeks that when I start my laptop all the time at 7900 to 8100 RPM. This is shown to me in Asus' own program and this can also be heard clearly. In an external program, however, I'm shown that the fan only runs at 270 RPM. It is only the CPU fan, the GPU fan behaves quite normally.
You can change this in the Bio Settings. However, I would not recommend changing anything.
Open it up and have a look - it is probably creased. This is faster and is safer than all internet research.
Take a look at https://www.hwinfo.com/download/ (portable version is enough) and take a look at the temperatures of the hardware (CPU, GPU, possibly hard drive). But I also suspect that if the device is older, the cooling system simply has to be cleaned.
