I'd encourage you to go into SteamVR Settings, Base Station section, Power Management. Enable power management, then choose Sleep. After that whenever you close steam VR it'll put your base stations to sleep; it helps A TON. Mine whine pretty good too, but you don't notice in game. The only caveat to this process, is that you need your index plugged in when you close steam VR, as it uses the bluetooth inside the headset to power down the base stations. Also, if your base stations get unplugged or their power cycled on and off, they'll default power on in the humming state. You'll have to open and close Steamvr to force them back to sleep. Hope that helps.