> putting the laptop under load makes the coil whine go away Probably be sub-harmonic oscillation. Under light loads the control loop can 'hunt' at a much lowe

> putting the laptop under load makes the coil whine go away Probably be sub-harmonic oscillation. Under light loads the control loop can 'hunt' at a much lower frequency then the loop frequency. Combine that with an unlucky inductor and you get a high pitched whine. It's an annoying problem because in susceptible designs it'll show up in a small percentage of some but not all production lots. Take your laptop back.