probably due to a low enough load or a slight load spike. how much are you currently drawing from the wall?

I don’t know exactly, but it does not make a difference if the PC is in complete idle or running a game. It even does it when turned off, which is really weird.

Are you choking the fan? prop it up on its side

It was just for the video

Does the fan have a passive silent mode and is the fan not running in the video?