My PC suddenly powers off as if the electricity was cut, even while idle, doing light editing, or playing Netflix. CPU, GPU, motherboard temperatures, and software-reported voltages look normal. After the shutdown, pressing the case power button does nothing until I turn the PSU switch off and back on. The mouse remains lit, so standby power is still present.
Once it starts again, it may run for only 5–30 minutes before shutting down, although it has occasionally lasted an hour or even several days. A different generic PSU allowed the system to run for about two hours, and reinstalling the original PSU temporarily made the problem disappear for five days. It even handled several hours of gaming before shutting down again while watching Netflix.
I have reseated the RAM and cables, reinstalled Windows, removed the hard drive, tried another SSD, and removed the dedicated GPU. The system uses a Ryzen 5 5600G with integrated graphics. Could the PSU still be failing, or is the motherboard more likely? Can a CPU cause this kind of shutdown even when temperatures are normal?
4 Answers
Cooling is worth checking even though the reported temperatures look fine. Confirm that the CPU cooler is mounted properly, the CPU fan is connected to the correct header, and the case fans are working. Some Ryzen systems can shut down during boost behavior if cooling or fan monitoring is faulty, but the PSU should still be tested first.
If you can borrow a reputable PSU with enough wattage, run the PC with it for several days under both idle and gaming loads. The temporary improvement with the other PSU is useful evidence, but a generic model is not a reliable long-term test and could introduce its own risks.
The PSU is the strongest suspect. Having to switch its physical power button off and on before the computer will start again sounds like an internal protection circuit is tripping or the PSU is failing to recover. Software voltage readings and normal temperatures do not rule out brief PSU faults. Test with a known-good, quality PSU rather than another generic unit, and replace the current one if the issue stops.
If the shutdown continues with a proven-good PSU, investigate the motherboard’s power-delivery or protection circuitry next. Also test the RAM one module at a time and inspect for a loose screw or other case short. CPU failure is possible but much less likely here, especially since the system can run demanding games normally and the required PSU power cycle points more toward the PSU or motherboard.
The spare unit I tried was generic, so I’ll look for a known-good branded PSU instead of relying on that test.