Hi I have a Logitech G510 keyboard since I bought the keyboard the USB port has had a high pitched ringing noise coming from it, if I unplug the keyboard it goes away, plug it back in it comes straight back, it only happens when the PC is off.
The motherboard is an Asus m4a79xtd evo motherboard, thanks.
Turn your PC off then your power supply off and then unplug your power supply cord from the PC. Now try to turn your PC on, that's to take care of the static. It can be many things. Some old monitors make this sound when the PC is not running and I have heard it coming from broken or damaged hubs.
Reconnect the USB afterwards to see if the noise gone.