How to Reinstall Windows 7 on Your Computer from a System Image
Click Next in the following window, which confirms that you’re creating a system image of your (C:) (System) drive — the home of Windows, your programs, and your files.
Another window appears. Click Start Backup to start copying the system image to the drive. Depending on your drive’s speed, the backup consumes roughly an hour for each 200GB of files, but you can continue working while backing up.