According to the data sheet, it has 17400RPM, which is 290RPS, times 11 fan blades (if I counted correctly), so it would probably run with a 3190Hz sound. The noise is actually not that loud, given as 25dB(A) at 30cm.
While it is not overly loud, a proper case design that alleviates the annoying frequency by filtering it would be a good idea.