The PC fails to turn on following an electrical interruption in your neighborhood.
The PC fails to turn on following an electrical interruption in your neighborhood.
My previous (2009) PC with an ASUS P5Q SE Plus motherboard has generally functioned well, often operating as a server. In the past, during residential power outages I've faced no issues restarting the machine. Recently, a street-wide blackout lasted about eight hours, and when power resumed I was unable to turn the PC on. The green power LED on the motherboard is illuminated, but pressing the front panel power button yields no response. Neither do fans or lights activate, and there are no beeps from the speaker indicating any BIOS startup problems. The PSU (Cooler Master 650W Bronze) passed the vendor's test at the time and was disconnected from the motherboard, which resulted in fans, lights, and peripherals starting properly—indicating the PSU was functioning correctly. I've removed the power cable from the PSU, replaced the CMOS battery, and used a "clear CMOS" jumper. I'm planning to wait a while before checking if this resolves the issue. I'm beginning to suspect that the AC power conditions may have fluctuated when the grid came back online. Anyone have insights or similar experiences?
Thanks in advance for your help.
Regards,
Wayne
This issue is a pre-boot scenario, so I omitted the hardware specifications and operating system details as they weren't necessary for resolving the problem.
It's worth noting that the build might need more power than the existing 650-watt PSU can supply or sustain.
Also, the two printers and monitor were connected to the same power board with surge protection, and they are functioning properly.
It's good they're working, but it's important to verify if the surge protection is present and its rating. The age or condition of the equipment should also be checked.
It’s probable that the motherboard has a problem if the power supply is functioning well. A sudden power surge usually can’t pass through the supply without damaging it, though this isn’t a major concern now. For better reliability in the future, consider using a UPS to mitigate such issues. Even a brief power interruption, like a lighting strike, can harm a computer connected to a UPS.
Your next step should be to verify if the motherboard is linking the two pins you tested with a paper clip. Begin by using a multimeter to confirm that pin 9 reads 5 volts immediately after turning on the power switch on the supply. This voltage reflects the power the motherboard receives before it officially powers up. Most modern boards display a specific LED indicator right after activation—some have a fixed number of lights that change color.
Next, check whether pin 16, which should be a green wire, remains connected to ground when the power switch is pressed. This test is challenging because it requires the cable to be connected and may involve accessing internal connectors, which can be difficult. You might try testing it from outside the case, depending on what’s more convenient.
Alternatively, a simpler solution could be inspecting the front panel switch; if it’s faulty, removing it and briefly connecting the two pins might restore power to the machine.
As this is a pre-boot problem, I didn't add the HW specs or OS info since it did not seem relevant to the issue.
The voltages are all present on the
EATXPWR
plug from the PSU without load (when the 'paperclip' is inserted).
When I plug the connector back into the motherboard (leaving the paper clip inserted) then no voltages are present. The
PSON#
signal is grounded (TRUE) by the paperclip, but the PSU doesn't produce any output.
I want to swap out the PSU as the simplest action, but will have to purchase a new one to try, and it's doubtful the vendor will allow return/refund
🙁
The pin 9 (+5V Standby) shows 5V upon powering up or disconnecting the power supply, which is positive. The LED on the motherboard lights up correctly. Pin 16 (PSON#) reads 0V whether or not the paperclip is present, which raises concern. I attempted to short the front panel power button to mimic a press, but that didn't work. It seems there might be an issue with the motherboard or power supply, making it hard to determine which one is faulty without replacing them for testing. I don't have the budget right now, so I'll wait until further notice.
No other devices seem to have been impacted so far. The two printers and the monitor were connected to the same power board (which is said to have surge protection) and appear to be functioning properly. Maybe the motherboard's age is the reason for the issue. The PSU was replaced roughly four years ago, but it could still be involved.
This issue is a pre-boot scenario, so I omitted the hardware specifications and operating system details as they didn't seem pertinent to the problem.
It might be worth noting that the build could need more power than the existing 650-watt PSU can supply or support.
Also, the two printers and monitor were connected to the same power board (which claims to have surge protection) and are functioning properly.
It's reassuring they're working, but remember that cumulative surge protection matters.
Future outages or surges could be more damaging.
Check if the power board and PSU have sufficient surge protection and how old or worn they are.
Electrical issues often follow paths, especially during power restoration.
The motherboard and PSU could be involved.
Eventually, one or both might need replacement.
And then another outage or surge could occur.
Keep the overall context in mind.