I did almost all the steps which are commonly found on the Internet.
1. Unchecked automatic restart.
2. Opened the cabinet and installed external fan to cool down.
3. Updated several times even installed OS multiple times like windows 7, 8.1, 10 Android (remix os ) & Ubuntu.
4. changed the dward value in regedit.
Still don't have any idea of restarting by itself without warning. if you find sth valueable please do share with us. Sometimes it goes so good without any error but sometimes it just restart multiple times. At last i keep it switched off directly.