If the user during system installation or in system preferences to include the item Autologin, then the system should boot without entering login and password of the user.
But if you install and activate the new kernel or the proprietary video drivers, as auto-login adds a 10-second standby mode during the initial computer startup and logon:
To disable the 10-second standby mode when you turn on the computer and log on to the computer, it is necessary in the configuration file the MDM (Mint Display Manager) in the TimedLoginDelay line, set the parameter to 0 (zero) and save the current file.
To open a configuration file mdm.conf with administrator privileges, run in a terminal:
sudo xed /etc/mdm/mdm.conf
sudo nano /etc/mdm/mdm.conf
Save the changes to MDM.conf, close the editor.
After a restart, 10-second standby mode is disabled and the login happens directly.