I'd either return it for another one without the issue or call Samsung to arrange for repair or explanation.
However I ran into a consumer that had their ear on the keyboard and were complaining about the noise. Since they could not hear it a few inches away there was not much else to do but tell them to return it for a more suitable model that passed their ear to keyboard sound test.
As I writing, I have a terrifying sound like a sharp pebble being scratched on a piece of slate, coming out of my beautiful brand new Samsung 900X notebook, running on Windows 7. The sound is coming out of the top-left area of the keyboard near the power socket, around the "2" and "W" keys, which I assume is the hard disk.
Is this some awful trojan attacking my PC, or has a piece of grit entered an air vent to interfere with the internal workings? Or something else?