By default they are located at 'X:\Program Files\Mass Effect\BioGame\Config'. If it fails to do so, or if the files have incorrect data, the game will read the default config files that are located in the folder where you installed your game. (%SystemDrive% will be replaced with the drive letter where your Windows system is installed on following a colon, and %Username% with the current user that you are logged into the system with.)
All of the changes that are described in this article should only be tested on the files in the documents folder:
