So last night, when I go to shut my computer down, it immediately boots back up after shutdown. I try shutting it down several times, including holding in the power button right after it starts rebooting, and every time it reboots shortly after shutting down. I finally turn off the power supply after it shuts down and before it reboots. This morning, I turn the power supply back on, half expecting it to boot up on its own again, but nothing. The power LEDs on the motherboard and graphics card are lit, but even the fans don't spin when I push the power button. The computer is several years old, so I thought the power button might be going, so I tried plugging the reset button that I never use into the power button pins, but that didn't work. Neither did bridging the power pins with a flathead screwdriver. Is there anything else I can do at this point with spare computer hardware? And is this definitely a motherboard issue, or could it be the power supply or something else? Any advice is much appreciated.