Over the last few months I've noticed a really annoying high pitched noise in my room. I just figured it was one of the many devices in my room or maybe it was all in my head. Turns out it was my Logitech MX510 mouse! According to this great website Logitech is pulsing the wheel encoder LED at 5KHz and the harmonics create a 15KHz tone in one of the crappy capacitors. Solution? Just replace C11 with a 0.1uF tantalum capacitor. Also removed the metal thing under the scroll wheel to get smooth scrolling!