1, has nothing to do with whether the operating system is poisoned. It is mainly caused by the hardware (power supply, motherboard, and graphics card for the three suspected focuses), and it automatically restarts without reading the operating system. Secondly, there is a problem with the switch of the chassis.
2. Remove the power cable from the hard disk. Then test and troubleshoot. Frequent power off and restart, the hard disk is prone to bad sectors. A small amount of this phenomenon is hard disk failure (motor or circuit board), but it should be put in the last, first confirm the other OK, and then power on the hard disk (at this time if it is a hard disk problem, you will know).
3. Remove the chassis side panel, remove the switch between the chassis and the mainboard, and remove the cables from the restart button. Then connect the two pins of the switch directly with tweezers (there is a definition on the side of the pin that says Power on or PWR ON, plus or minus). If this is also a fault, the problem with the chassis switch can be eliminated.
4, replace the power supply to see. Many of these phenomena are caused by substandard power supplies.
5, if the power supply is changed, or the fault, change the video card.
6, if the video card is still faulty, remove the memory bar and wipe the gold finger with an eraser or alcohol (to remove the oxidation). Then wipe the gold finger in the memory slot on the motherboard.
7, if the above have tried, the fault is still in the motherboard. The CPU's voltage regulator power supply is damaged, resulting in sudden power failure or can not be powered on after the most common phenomenon.