Only one solution, use this 2 commands :
t.MaxFPS 50 (60 or 30)
r.VSyncEditor 1
Thanks to this settings, I managed to remove the buzzing. However, if you open something like Google Chrome while Unreal Engine is running in the background (but only on one screen, if you open on second it’s fine 
), you might still hear a slight humming sound, though it’s much quieter. I almost went crazy because of it, but now I can finally work in peace.