When you have installed Reason 8.3 and launch it for the first time, Reason automatically moves the Factory Sound Bank and Orkester sound bank to separate sub-folders in the following location on the hard disk (if they are not already there):
Mac: /Library/Application Support/Propellerhead Software/Soundbanks
PC: %programdata%\Propellerhead Software\Soundbanks
The factory sound banks will be located here so that Reason can be automatically updated in the future without affecting/deleting the existing factory sound banks. If Reason shouldn’t find the factory sound banks at this location, they will be automatically downloaded from the Propellerhead web site and put there.