I have a Nvidia GeForce 3080 with i9 10850k. This sound recently started happening. I first tried to remedy it with compressed air because the inside of the case was dirty because real life kept me away from my pc for 10 months. Now I'm back to it and I'm hoping this isn't really bad.
I should point out it does this when I'm playing games like fortnite, warzone etc. It continues doing this until several minutes after I close the game. Then eventually it gets whisper quiet again.