Scenario 3: The system randomly restarts and no Stop error BugcheckCode is listed, or the computer is completely unresponsive (hard hang)
To check whether this scenario is occurring, press the CAPS LOCK key on the keyboard. When you do this, if the CAPS LOCK light on the keyboard does not change when you press the CAPS LOCK key, the computer may be completely unresponsive (hard hang).
This scenario usually indicates a problem with the hardware. Another possibility is that a driver may cause this problem. To help isolate the problem, check the following items:
Overclocking: Disable overclocking and see whether the issue happens when the system is run at the correct speed.
Check the memory: Verify the memory by using a memory checker. Verify that each memory chip is the same speed and that it is configured correctly in the system. Power Supply: Make sure that the power supply has enough wattage to appropriately handle the installed devices. If you added memory, installed a newer processor, installed additional drives, or added external devices, such devices may require more energy than the current power supply can provide consistently.
Overheating: Check whether the system is overheating by examining the internal temperature of the hardware
Defaults: Use system defaults, and run the system.