The two major reasons why computers crash are operating hardware and operating system errors. While computer crashes that originate from errors in the operating system are easy to diagnose, those that are caused by hardware errors can be elusive.
Faults in the hardware vary in nature and effect. Crashes often originate from failures in the power supply, the RAM chip, the cooling system or dust. As these components age, they may develop faults. If the power supply is unable to play any of its roles in converting power from AC to DC, a computer crash is often sudden and unexpected. If a computer has two RAM chips, a failure originating from the RAM may take place after the computer has exhibited a slowdown. System fans are charged with the role of lowering the system temperature. If the fan does not play this role, the computer may overheat and crash. Moreover, the fan often draws in dust into the computer which may facilitate a computer crash. Blowing off the dust would resolve this problem.
A majority of computer crashes originate from the operating system. Due to the many roles the operating system plays, there are many opportunities for errors to occur. A system crash may arise if the computer OS attempts to gain access to an improper address. In that case, a general protection fault occurs, hence causing a memory crash. Another incident that may cause a computer crash is if the OS regenerates the same command causing a lock-up.