A:Answer The fan should make a noticeable whirring sound typical of most cooling fans, however the fan speed increases or decreases, along with the sound of the fan, as the power supply changes temperature. One solution is to make sure that your Xbox One S is properly ventilated. For more information on how to do this, go here: https://support.xbox.com/en-US/xbox-one/console/ventilation
If the noise remains unreasonably loud, then you may want to return the unit to Best Buy for a replacement.