My computer was working normally when it suddenly powered off completely. It now shows no signs of starting, although speakers connected directly to the PC by USB still have their power light on. I didn't notice a burning smell or any other obvious warning signs, and the motherboard power connectors appear secure.
The system uses a generic 450W FiercePC ATX-450 Silent power supply, a Ryzen 5 5600G, a Radeon RX 5600 XT, and a Gigabyte B450M motherboard. The computer is about four years old, while the graphics card was installed around three years ago. I've never been particularly confident in the power supply's quality, so I'm wondering whether this sounds more like a PSU failure or a motherboard problem. What should I test before replacing parts?
2 Answers
The motherboard could still be involved, but a failed board often gives some combination of fans spinning, repeated restarts, diagnostic lights, or other intermittent behavior first. If pressing the power button produces absolutely nothing while standby USB power remains, the PSU is a strong suspect. You can also briefly test the case power-switch connection by momentarily bridging the two power-switch pins with a screwdriver, but only after disconnecting power and confirming the pin layout in the motherboard manual.
A sudden, total shutdown with no gradual instability is more suspicious for the power supply than the motherboard. The USB speaker light only proves that the PSU is still providing standby 5V power; the main power rails can fail while USB devices or motherboard lights remain active. Given the age and unknown quality of that 450W unit, testing with a known-good PSU would be the most useful next step. Choose a reputable model with enough capacity for the 5600 XT rather than another generic replacement.
That makes sense. I already suspected the PSU since it’s a generic unit and I’ve never found much reliable information about its quality.