My PC Self-reboots: A faulty Power Supply Unit (PSU)
So the electrical connection is not the problem. Let’s move on to the Power Supply Unit or PSU (unless your PC utilizes a UPS instead. This will be covered in the next post). The PSU is the most common cause of self-rebooting. The best way to troubleshoot this is to replace the PSU (TIP: When replacing a motherboard, also replace the PSU). There are good quality PSU out there and they come in relatively cheap prices. Do not attempt to replace it yourself if you have no idea on how to do it. Better take your PC to a repair shop.
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