Power supply crackling and clicking

I’ve recently bought a prebuilt pc from pc specialist and i’ve ignored clicking for a while i got told it was my aio but it wouldn’t always click sometimes it would and sometimes it wouldn’t but when it does it doesn’t stop for a while until i close a game or ect i put my ear to the power cord at the back of the pc at the bottom the clicking gets louder so it’s 100% that i’ve been told to power it off and do not power it on again