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You should start your own thread, the OP didn't get a response with his description.
It really could be anything, The sound is either a fan or your Hard Drive.
For a desktop you substitute parts or try your parts in another computer. With a Laptop you have to do the same thing, but except for hard drives CPU,and memory, it is harder to find parts or another computer exactly the same. If it is not the HD, CPU, or Mem, the rest is pretty hard to fix.
Only a manufacturer would have a test device for their own laptops.