The sound of the PSU fan was driving me crazy, so I replaced it with the front header fan. The front header fan is still connected to the motherboard, so I set it to act like a PSU fan in BIOS. But the thing is, how would the motherboard control this fan properly if it doesn't know the temperature of the PSU? And why is there even a "PSU fan" option in BIOS if motherboards don't know the temperature of the PSU?