I did have a similar problem with a macintosh that i bought last year and couldnt do anything to get rid of it - but as the computer was under guarantee i sent it back and apple fixed the problem and i had the computer back in 2 days. i would try and contact the shop you bought it from - there is no way it should be making that noise when it is so new, i know it isn't a big deal but it can be very annoying and could be an indicator that something else is wrong. sorry not to solve the problem, but it is a start...