Fans maxing out

Hi all, I got my younger brother a pc the other day said hand. It’s an Acer nitro 50 with rtx3060.

Got a good deal of a friend.

Performance wise it’s plenty capable for what he needs but had some slight temp problems.

I bought a new CPU cooler and 2 case fans to replace the previous 1. All fitted fine but it was going to 4000rpm for literally no reason, temps were like 40C and it was sounding like a jet

There’s no option to alter this through Bios. I tried using a few third party softwares like speed fan and the MSI afterburner (i think it’s called) but these didn’t help at all

Refitted the previous fans and the problem persists.

I’m at a complete loss and any guesses to what this is would be appreciated please

Thanks in advance