The PC will start only if the power button remains pressed and the PSU is activated at the same time.
The PC will start only if the power button remains pressed and the PSU is activated at the same time.
I’m dealing with a completely new problem I’ve never encountered before during my years of assembling and repairing PCs. When the system powers down, it won’t automatically restart unless I also disable the PSU power switch and then turn it back on while keeping the case power button pressed. I’ve replaced the PSU and the case power button, CPU, and motherboard appear fine otherwise. The thermal paste stays below 70°C on both the CPU and GPU during heavy usage. This issue started earlier this week. After swapping the PSU for a new one, the case switch malfunctioned, causing it to overheat and smoke. I’ve salvaged an old tower’s power switch and still face the same problem. In the BIOS, nothing has changed, and I’m the only user with access to this machine.
I’m really puzzled about this. All my research points to a PSU failure—possibly due to failing capacitors, a loose Front Panel connector, or a defective power button mechanism.
Hello Sir
Please verify if you also swapped all the modular cables when replacing the PSU. Even if the PSU models match in wattage or brand, using non-standard cables can lead to voltage errors, power latch problems, or component damage, such as the front panel circuitry.
Since the power switch smoked, this might indicate a cable incompatibility or power delivery issue rather than a BIOS or thermal fault. I hope this clarifies your concern.
The problem began before I replaced the power supply units, though I believed I had swapped all the cables just to be cautious in case it was a faulty cable. However, I overlooked the one connecting to the front panel hub, which caused the case switch voltage regulator to fail when I attempted to power it on. The issue continued even after using the new switch. I suspect the motherboard itself might be the cause, as it seems to misinterpret the CPU fan header connection. I had to turn off that setting in the BIOS to allow booting past the BIOS now.
I’ve experienced power interruptions and tripped circuit breakers several times. My surge protector works well, but I don’t have a backup power source for safe shutdowns during outages—something I never encountered before. Although I’ve used a regular surge protector for over 20 years without issues, things can change with time.
The motherboard is still under warranty, and I plan to chat with ASUS tomorrow. They asked not to submit an RMA if there are safety concerns like electric shock, chemical leaks, smoke, fire risk, damaged components, injury, or property damage. While I don’t believe any of these are present, it would be wise to discuss it first. I’m unsure if the CPU is the problem here.
EDIT and Update: I found that one of my hard drives or SSDs isn’t being detected even though it’s plugged in.
If I were in your position, I'd also send a return request for the motherboard.
The power switches on all my PCs are straightforward (passive) momentary action push button switches, with two wires connecting to a header on the motherboard. There is no active circuitry linked to the switch that needs connection to a power supply. The switch leads are fully isolated.
I've never encountered a voltage regulator tied to a front panel power switch. It would be unusual for a problem to arise from feeding power into the wrong USB hub inputs, though it's not impossible.
If a +5V or +12V DC supply rail somehow fed back into the power switch input on your motherboard, it could have damaged some of the circuitry and you might need a new motherboard.
More likely, the incorrect connection to the hub fed back into a USB header or fan connector on the motherboard, rather than through the switch leads. This poses a serious risk and could also harm the CPU, RAM, GPU, SSD, and possibly the motherboard itself. Changing the motherboard may fix it, but I can't guarantee it.
You cannot be shocked by a motherboard unless it's connected to a voltage above the SELV limit, so this safety warning seems unclear. I used to verify "safety critical" components in power supplies as part of my engineering role.
When a faulty motherboard is returned in an ESD bag, it's not connected to a PSU and should be fully de-energized. The maximum voltage applied to a standard PC motherboard is +12V, which is well below the SELV limit. Any charge stored on motherboard capacitors should have dissipated within a few tens of seconds after switching off.
Given all these points, it's surprising that manufacturers or dealers would accept any returns. They haven't prepared for nuclear war, tsunamis, or earthquakes—what do you think?
I'd simply return the motherboard to Asus without going into too much detail, since it seems your fault likely caused the damage. If they find out you unintentionally harmed the board, they might refuse the RMA. The guarantee covers manufacturing defects, not user misuse. You might have a chance.
If you were to drop a brand new car into a fire hydrant, would you expect them to replace it after you caused the damage?
I already know the Lian Li Evo 11 XL case has the fan controllers and RGB controllers connected to the front panel and power switch circuit board, and it needs a SATA power connection. I noticed this problem began before I replaced the PSU, and the switch sparked, causing a fire. I plan to reach out to ASUS to find out exactly what I need for an RMA, hoping they can send a replacement instead of sending me back for repairs. I really don’t want to be without my PC for too long. Thanks for the advice!