[beagleboard] High pitch squeal with using 5V power connector.

Something is wrong. I have never heard a board squeal as you describe. Can you isolate exactly where on the board it is coming from?
What is the current rating of the supply? What is plugged into the board?

Gerald

Just a guess but it sounds like a bad capacitor. Didn’t I see a fairly large one (compared to other components) on the new board ?

The switching supply on the bone? (faulty inductor)

We use chip inductors, so nothing there to vibrate. And, the USB power uses the same inductors and under USB power and their no noise. All the voltages are the same whether under 5V or USB power.

Gerald

Hmmmm L