My Dell XPS13 does that and it’s super annoying. It’s some kind of cross talk with the speaker amplifier because when I mute the sound or use headphones it goes away.
When I was a kid our BBC Micro used to do the same, you could “hear it thinking”.
Yep, my XPS does too. I believe it's called "coil whine" and is caused by surface-mount inductors whose windings aren't fully encased in resin or whatever material they use.
When I was a kid our BBC Micro used to do the same, you could “hear it thinking”.