Don't open the PSU, unless you know what you are doing with electrical equipment you risk electrical shock, possibly electrocution as there is tremendous amounts of energy stored in capacitors even in a off or unplugged PSU. There's been sever stories over the years of people being injured and even killed attempting to "fix" or "upgrade" power supplies.
Replace the PSU. Your current unit(even if the fan was fully functional) is low quality to the point of being a danger to the system.wow ok , you really scared me xd . is any soultion to stop that noise
Hopefully you can still return it then.that's sad i buy it a weak ago
anyway tahnk's richiestang_78 and bignastyid for your advice