Case 1: CPU fan is broken
Resolution: Replace the fan
Case 2: CUP fan is fallen and separated from the CPU.
Resolution: glue the fan to the CPU.
Case 3: Laptop is overheating
Resolution: Get a Laptop Stand
Case 4: Run third party software to check CPU temperature. If the CPU is overheating, that will lead to shutdowns.
Resolutions are: Clean fan bay on laptops or CPU cooler on a desktop; Change the thermal paste; Use the cooling pad of some kind to reduce heating; Change overclock settings to default; Use external fab to cool the system.
Case 5: Bad memory
Resolution: Many PC BIOS comes with test toll. You can run memory test to make sure the memory is good.
Case 6: Bad battery
Resolution: Replace a new battery
Case 7: The Laptop battery is critically low
Resolution: 1. Replace the battery.
2. Take the battery out and plug the AC to the wall.
Case 8: Bad HDD sectors
Resolution: Open Command Prompt running as admin. Type this command: chkdsk /r to check the hard drive state.
Case 9: BIOS issue
Resolution: Update BIOS
Case 10: Malware or virus
Resolution: Scan malware or virus. In Windows 10, You can go to Settings>Update & Security>Windows Security.
Case 11: Windows 10 issue
Resolution: Perform a clean reinstall. More info can be found here:http://howtonetworking.com/Windows/w10howto.htm
Please view this step by step video: