ATX Desktop Power Supply: Unstable power-good signal | Auckland
Pattern to record: Startup loops or resets occur before POST despite normal unloaded voltages.
Identify the supply and load
An ATX power supply provides several outputs and startup signals. Document the PSU model and connected loads; a spinning fan or a simple unloaded start test does not establish stable operation under load. One possible explanation is that the supply does not reliably indicate that output rails are ready.
Mains and connector safety
Power supplies contain lethal mains sections and should not be opened casually. Forcing the signal high can expose the motherboard to unstable voltage.
Workshop checks
- Measure standby and loaded rails with known hardware while separating PSU from board faults.
- Monitor the power-good timing and rail stability through startup.
Repair and loaded verification
If the checks support this cause, replace the supply or repair its control stage professionally. Verification should cover cold start, processor and graphics load, sleep, restart and all required connectors.
For an assessment of your desktop PC, contact AEPC in Burswood or call 027 908 8880. Provide the model and the conditions that reproduce this problem. Workshop visits are by appointment.