Lenovo G400s Touch User Manual page 35

When do I need to change the boot mode?
The default boot mode for your computer is UEFI mode. If you need to
install a legacy operating system, such as Windows (that is, any operating
system before Windows 8), Linux or Dos, etc., on your computer, you must
change the boot mode to Legacy Support. The legacy operating system,
such as Windows, Linux or Dos, etc., cannot be installed if you don't
change the boot mode.
Getting help
How can I contact the customer support center?
See "Chapter 3. Getting help and service" of Lenovo Safety and General
Information Guide.
Chapter 4. Troubleshooting
31