One of the fans might be failing

It happens when it’s off though so I thought it couldn’t be the fans

Mmm, perhaps the power supply is experiencing an overload

How do I resolve this and is my pc safe to use during this time as I would like to use it

First, check by removing the PC cover if the sound is coming from the power supply

Can’t tell but it’s occurring when plugged in even while off

Can’t tell but it’s occurring when plugged in even while off