I upgraded my Opnsense box from an old fanless mini PC to a spare full-size PC I now have. Everything is working fine except that this machine has both a CPU and case fan and these seem to be stuck on max speed. Can I control the fan speeds and how would I do that?
Try PowerD under System: Settings: Miscellaneous.
Most BIOS let you set the fan speed, or you can try an in-line resistor/varistor to reduce the speed.
Bart...