I built this PC myself, and it had been working normally for about eight months. I left it unused for roughly 50–60 days, and now it will not start. The mouse lights up, so the motherboard seems to be receiving some standby power, but pressing the case power button produces no motherboard response and none of the fans spin. I already tried briefly shorting the power-switch pins on the motherboard, but that made no difference. The system uses an MSI B550M PRO-VDH WiFi motherboard, Corsair RAM, a Gigabyte RTX 3060, and a Cooler Master MWE V3 550 Bronze PSU. There was a recent power outage, although the PC was connected through a UPS. What should I check first?
2 Answers
You can test the PSU separately by following the manufacturer’s jumper-test procedure, with the PSU disconnected from the PC. However, that test only shows whether it starts up and does not fully prove that it is healthy under load. If you are new to PC building, borrowing a known-good PSU or taking the system to a repair shop is safer and more conclusive.
A lit mouse only proves that the PSU is providing standby power; it does not prove that the main 12 V outputs are working. The PSU could still have failed, especially after a power event, or another component could be preventing it from starting. Testing with a known-good compatible PSU is the most useful next step if you can borrow one. Do not open the PSU itself.
I do not have a spare PSU. Mine is a Cooler Master MWE V3 550 Bronze, so I may need another way to verify it.