actually the only parts on a PI2 that could create audible sounds, are the coils of the switching converters, and in theory some ceramic capacitors that could have a piezo-electric effect.
Silicon chips don't make any noise (except for a loud bang when you put much to much voltage on them, 240V AC on the 5V input for example
these noises should be very-very faint, but if you are unlucky and the board vibrates on a harmonic of the part it might get louder, and more distinct.
but this should not be anything you should worry about, at least not normally, if you put 5.7 Volt on a PI things could be different.
You could try if things change with another power supply.