Issue with starting the system on multiple identical computers. Please let me know if you need further help!
Issue with starting the system on multiple identical computers. Please let me know if you need further help!
Three years back I bought twelve identical PCs from a UK prebuilt supplier for professional use. Each unit matched perfectly and functioned without problem for three years until recently. I encountered problems with three of these machines, all located in the same office. Initially, one PC failed to power on after shutdown during the night and would restart in the morning. At first, it was just one unit, but soon all three began experiencing the same issue.
The problem started with the front panel power switch not engaging when the PC was turned off overnight, then activating in the morning. It was an intermittent fault at first, affecting only one machine. After disconnecting from the power source and retrying multiple times, they would unexpectedly turn on. The situation worsened with the first PC, leading me to suspect a power switch failure.
I replaced the switch and everything seemed normal for a few days, but it recurred again. Believing the issue was with the power supply unit (PSU), I swapped it out with a verified working model of the same type. However, the PCs still wouldn’t power up. I then attempted to bypass the switch on the motherboard, but it had no effect. The mainboard displayed lights but showed no fan activity from the PSU, CPU, or motherboard.
I suspected another component or connection problem. I disassembled every part—motherboard, CPU, PSU, RAM, GPU, SSD, and front panel connectors—essentially treating it as a complete system. Even after shorting the power switch pins and using a switch, nothing happened. I also removed the CMOS battery for further testing.
Convinced it was either the motherboard or CPU, I removed the mainboard from its chassis to check for a short circuit. It was left overnight, and I tried again the next morning with a clean setup, as I was very frustrated. It worked perfectly on the workbench where I left it. After shorting the pins, it powered on! I was amazed. I connected each component individually and everything functioned correctly, including the power switch. I tested shutting down, restarting multiple times, and leaving it off for hours—it always started up without issue.
A few days later, the two other PCs in the same office (identical specs) began showing the exact same problem. After disassembling them and shorting the pins, they also failed to power on. I left them overnight again, and surprisingly, they worked fine the next day.
I’m seeking clarification on this situation, as I’ve never encountered anything similar before. We have nine more of these units in other departments, all functioning properly. I assumed a power surge might be the cause in my office, but I was working on these PCs in a separate building. Here are the details:
- CPU: AMD Ryzen 5 3600X
- Motherboard: ASUS PRIME B450-PLUS
- RAM: 8GB Corsair VENGEANCE DDR4 2666MHz (2 x 4GB)
- Graphics Card: 1GB NVIDIA GEFORCE 710 - DVI, HDMI, VGA
- SSD: 250GB Samsung 860 EVO 2.5"
- Power Supply: CORSAIR VS-350
Just for you... compare the input power in your office with the other one.
Thanks for your reply. I was thinking that it could somehow be a power issue in the office, but they seem to run fine unless they are shutdown overnight. When I tried to power up the pc's in a different building, still nothing. It's so bizarre that leaving them overnight enables them to power on again the next day is if nothing has happened. There must be a common explanation, as it's happening to 3 identical pc's. We have booked an electrician to test the power in the office, but I cannot see why it would cause this. I would expect a surge to kill the board or components.
Since you've already gone through the rest of my message, it's clear that this model is likely experiencing a failure. From your description, potential causes could include
Manufacturers may have used faulty capacitors. Early intermittent failures support this theory.
Other component weaknesses are less common, though power transistors (particularly in SMTP voltage regulators) don't usually behave this way and are less likely to be the issue (capacitors remain the most probable).
Another possibility involves material selection errors, such as direct contact between copper and aluminum that leads to corrosion over time.
Additional details: For capacitors and material choices, the rate of degradation can differ based on environmental factors like humidity and temperature—this might explain why some offices are affected sooner.
However,
Also, keep in mind external factors. If your building has subpar electrical wiring or the local power company struggles with voltage stability (more prone to spikes), that could play a role.
Contrary to common assumptions, a voltage spike can indeed pass through SMPS circuits—standard power supplies—and cause damage to the main computer board. In such cases, the first affected office might be closer to the nearest circuit breaker panel. If other offices are on the same branch circuit, it makes sense that the PC first because its input circuit has some protection against voltage spikes, acting as a weak over-voltage safeguard.
Do you anticipate the PSU fan turning on right after power is applied?
Thanks for your detailed reply. The thing that baffles me is that the mainboards or components are not being damaged because they eventually work after leaving them untouched overnight or longer. It's almost as if the CPU or motherboard (nothing else was connected, PSU swapped) goes into a lockdown state after a power on the next morning after being shutdown overnight. I don't expect the PSU fan to come on from initial power up, but the chassis and CPU fans certainly. The build components are pretty mainstream and are not what I would class as bottom of the pile or poor quality. It's a very simple office pc build with stock air cooler for the CPU and no memory overclocks for cpu or ram. I chose these over a standard Dell unit as there were better upgrade options and the components were (on paper) better. I am very open for it to be a particular issue with the hardware, but I cannot think of anything else except the motherboard and CPU that would be the issue. 9 other pc's of the same build and age are still running in other offices with no issues.
Have you explored alternative CMOS batteries?
Unstable performance linked to prolonged periods without power can indicate a low-voltage battery.
Additionally, the PSU OCP and OVP circuits may require time to stabilize after a power surge.
Stray PoE issues? Voltage induction into Ethernet, grounding problems between sites? I measured 50V AC flowing through a parallel cable over roughly 50 feet. The fix was installing a fresh ground rod close to the equipment—my computer was in another room due to dust concerns.
I attempted to remove the CMOS battery for a few minutes on one of them, but it had no effect. I didn’t believe a weak or dead CMOS battery would stop the system from starting. I plan to use fresh batteries now. The other points you made are beyond my understanding. I was curious about your 'stray PoE' remark. Unclear what it means, but I can tell that these PCs have been moved to the office and are now linked to a PoE switch (previously non-PoE). It’s actually a 48-port Cisco Catalyst PoE switch. I’m not aware of any other devices connected to this switch that are having problems. There are other offices using the same model of PoE switch with identical computers and haven’t encountered any issues.
I still don’t grasp how a computer can be reduced to just a power supply, motherboard, and CPU without even posting (only the mainboard LEDs light up) by shorting the power pins on the motherboard connector (not the 24-pin ATX board). Yet, it powers up automatically when the pins are shorted or connected to a power switch. As I mentioned earlier, even swapping in a fully functional PSU didn’t help. It seems the motherboard (or CPU) might enter some kind of power-on prevention mode.
Probably someone has dealt with this situation before.
Improperly connected ethernet cables combined with PoE may result in unexpected voltage levels. Be aware of this possibility. Memory is required for POST; the CPU cannot operate independently. POST involves analog electronic processes, and any issue in power circuits can stop a circuit from maintaining a state. Therefore, a defective or leaking part might cause insufficient voltage where it shouldn’t, leading to POST failure. If several units from the same production date exhibit the same issue, it likely points to a widespread problem.