I've owned my PSU for now 4 years (Seasonic S12G 750W) and since day one it's always made a low constant buzzing sound which I associated to coil whine.
Now yesterday, I upgraded my GPU to an Asus ROG Strix 2080Ti and when I play an intensive game, the buzzing from my PSU gets louder and I can also hear the same exact sound coming from my GPU. When I go into the pause menu it immediately stops.
Weird thing is I tried running Furmark: total silence. Same with Cinebench, nothing. It only seems to happen when I play a game and both my GPU and CPU are