If this thumping noise is similar to what you hear when you are starting your computer, then your hdd is dying, or perhaps you have issues with your power supply/cables. Try to see if you can get the same behavior, installing the hdd into another computer.
Usually hdds have the same number of platters. The density at which they can store data, makes the capacity difference.

HDD thumping noise
What should I do to establish rights on my work? Does it depend on the country where it was created?
