My power button no longer turns off my PC

KevTech "Explain to me how commands for Windows has anything to do with the bios."
In normal operation the shutdown command does, in fact, shut down the computer. So, you need to think through this process and ask how are these related? How does a windows command remove power from the computer motherboard? Next, ask yourself what is the BIOS and what does it control. By just going through the settings on a typical BIOS you should get the idea that the BIOS controls the components and functions on the motherboard. And there you have it - a link between a windows command and the BIOS. The shutdown command tells the BIOS to remove power from the motherboard.
One other way in which the shutdown command can help diagnosis the problem is to cast doubt on the mechanical or electrical connectivity of the computer's power button.

Scott "Not sure how the latest BIOS version would affect his power button"
See above explanation to KebTech. The original BIOS on the computer was developed by people who designed, built and tested the computer. Any updates in subsequent years come from people who often have no idea what's in the BIOS code and are "fixing" just a small portion in response to the latest vulnerability hysteria. Just like Windows Updates, there is no guarantee that a BIOS update is going to work. Just because it's the "latest" does not mean it's the best, or the most appropriate, or compatible, or that the user didn't screw up something in the BIOS installation or settings.

Scott "I say always keep you BIOS up to date. I have, and never had any problems."
You are just one lucky person out of the 2 billion people using Windows computers.

SumpterX said:

How does a windows command remove power from the computer motherboard?

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shutdown /s tells the Advanced Configuration and Power Interface to transition the system into a low-power "Soft Off" or S5 state.

A software command relies on the operating system running.

Go ahead and see where there is a place in the bios to enter a shutdown command.

KevTech said:

Go ahead and see where there is a place in the bios to enter a shutdown command

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Not sure what you're saying. The APCI code (firmware) is implemented in the BIOS/UEFI. The BIOS/UEFI does not have a shutdown command, but it has settings for power management. Yes, William654 should go through all the BIOS settings and see what is related to power management.

SumpterX said:

The BIOS/UEFI does not have a shutdown command, but it has settings for power management.

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So does Windows in device manager.



The BIOS does not control the Windows shutdown /s command because that command is an operating system feature managed by Windows, though the BIOS handles the final physical power-off sequence.

But your statement that if shutdown /s does not work the bios is corrupt is incorrect.

At first I thought the problem was caused by a faulty power switch because the computer would not power off when in the BIOS. However, you also said the computer would also not power off when shutdown is selected in Windows. That indicates either a faulty motherboard or power supply.

IF his power plans are corrupted (failed attempt to change earlier in the thread) could that have an impact on how his power button reacts?

Asus272 said:

IF his power plans are corrupted (failed attempt to change earlier in the thread) could that have an impact on how his power button reacts?

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The problem happens in the BIOS also. Anything in Windows like the power plan has nothing to do with that.

William654 said:

Not fully replaceable but i also have external button i can use. I will remove the power connector and test with screw driver to short the pins and test if holding the screw driver for 5 seconds will execute normal shutdown

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If you want to rule out if you have a corrupted windows install.

If you have a USB with Windows install, boot from the USB with the Bios boot menu or set USB as first boot option.
When you start windows install and you get the first box of continue... Press Shift+F10 to get the Command prompt. (on some laptops, you need to press Shift+Fn+F10)
Then in the Command prompt type: shutdown /s /f /t 0
and hit enter..
( the switches: /s shutdown the computer. /f force close without ask for confirmation. /t 0 set shutdown timeout to 0 seconds. )

if the computer shut down without any issues, you have a corrupt windows system... If it still refuse to shut down, you might have a hardware related issue.

If you have a Live Linux USB stick instead of a windows installer stick, then you can boot that Linux USB-stick the same way from Bios boot menue or set USB as first boot and from that Linux live environment click "start"menu, click shut down the computer, to see if a software shutdown works.


You say you have an UPS and the computer wont turn off until you unplug the UPS.. Do you have a USB cable between the computer and the UPS for a controlled shutdown... If you have that, unplug the USB cable and try normal windows shutdown.

The OP probably needs to do a reapir install to fix the corrupted power profiles. Also the OP has not yet done the PSU test - search for "PSU paper clip test"

Steve C said:

The OP probably needs to do a reapir install to fix the corrupted power profiles. Also the OP has not yet done the PSU test - search for "PSU paper clip test"

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I found the test from the same psu company

But what it test ? If the psu working?

AI is good at breaking down a problem and formulating a plan to help you diagnose it:

Since the issue occurs even when pressing the power button inside the UEFI/BIOS menu before Windows boots, this is a hardware or low-level motherboard state issue rather than a software or Windows driver problem. The motherboard is failing to send or signal the PS_ON# state to the Power Supply Unit (PSU) to drop the primary power rails.

Root Causes & Solutions​

1. Stuck System Management Bus (SMBus) / Power State (CMOS Glitch)
   
   • Cause: The motherboard ACPI/power state management unit can get hung up in an intermediate state, keeping the power rails active even after shutdown commands.
   • Fix: Clear CMOS completely. Turn off the PSU switch, unplug the PC from wall power/UPS, remove the CR2032 coin cell battery on the motherboard, and press and hold the case power button for 30 seconds to drain residual electricity. Reinsert the battery after 5 minutes and power back on.
   • Verification: Boot into BIOS and press the power button once. If the board shuts down cleanly within 4 seconds (or instantly), the ACPI controller state has reset properly.
2. Power Supply Unit (PSU) Fault or PS_ON# Signal Latch
   
   • Cause: A malfunctioning power supply (or a failing +5VSB / standby control circuit) can remain latched on high voltage rails (+12V/+5V/+3.3V) even when the motherboard toggles PS_ON# to off.
   • Fix: Test with a secondary spare PSU if available, or test the PSU independently with a paperclip bridge test (PS_ON to GND) to see if it powers down immediately when bridged pins are disconnected.
   • Verification: If swapping the PSU resolves the hanging fans/LEDs immediately upon shutdown, the original PSU's internal control board is faulty.
3. Faulty PCIe / USB Peripheral Back-Feeding Power
   
   • Cause: Powered external devices (USB hubs, powered monitors, sound cards, or UPS communication cables) can back-feed current through motherboard ground or data lines, keeping system power circuits energized.
   • Fix: Unplug all external peripherals except a single monitor (DisplayPort/HDMI) and keyboard/mouse. Disconnect any USB communication cables connected to the UPS.
   • Verification: Attempt a shutdown from BIOS. If it shuts down normally, reconnect devices one by one to isolate the culprit.
4. Short Circuit / Front Panel Header Pin Issue
   
   • Cause: A shorted power switch cable, stuck front panel switch, or improper header wiring can keep the power circuit signal bridged.
   • Fix: Temporarily unplug the POWER SW header connector from the motherboard's front panel pins (JFP1) and use a screwdriver tip to momentarily short the two power pins to test power-on and power-off behavior.
   • Verification: If shorting the pins manually allows a proper shutdown while the case button does not, the case button switch or wiring is defective.

1.Perform a Full CMOS Hard Reset:Hardware.
Unplug the PC from power, remove the motherboard CR2032 battery for 5 minutes, press the power button for 30 seconds to drain capacitors, and reinstall the battery.

2.Disconnect Non-Essential Peripherals:Isolation.
Disconnect all USB devices, external hubs, sound cards, and UPS monitoring cables, leaving only keyboard and primary monitor connected.

3.Bypass Front Panel Power Button:Testing.
Unplug the case POWER SW cable from JFP1 header and bridge the power pins with a screwdriver to test manually.

Did this start happening suddenly after a specific hardware change or BIOS update, or has it been ongoing since building the system?

Asus272 said:

Type shutdown /s /f /t 0 and press Enter

Click to expand...

Problem remain

Asus272 said:

Short Circuit / Front Panel Header Pin Issue

• Cause: A shorted power switch cable, stuck front panel switch, or improper header wiring can keep the power circuit signal bridged.
• Fix: Temporarily unplug the POWER SW header connector from the motherboard's front panel pins (JFP1) and use a screwdriver tip to momentarily short the two power pins to test power-on and power-off behavior.
• Verification: If shorting the pins manually allows a proper shutdown while the case button does not, the case button switch or wiring is defective.

Click to expand...

Just tried now and the problem remains

William654 said:

yourProblem remain

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You have a hardware problem that needs to be addressed but your boot drive has problems also. Since it still boots it should be recoverable but their is a strong possibility that it could get worse by continuing to boot it. Do you have recent backups of your boot drive? Are you comfortable doing the required hardware tests?

Asus272 said:

your boot drive has problems also. Since it still boots it should be recoverable but their is a strong possibility that it could get worse by continuing to boot it.

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Why ? I dont understand

Asus272 said:

Do you have recent backups of your boot drive?

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yes

Asus272 said:

Are you comfortable doing the required hardware tests?

Click to expand...

yes

Do this one next

• Fix: Clear CMOS completely. Turn off the PSU switch, unplug the PC from wall power/UPS, remove the CR2032 coin cell battery on the motherboard, and press and hold the case power button for 30 seconds to drain residual electricity. Reinsert the battery after 5 minutes and power back on.
• Verification: Boot into BIOS and press the power button once. If the board shuts down cleanly within 4 seconds (or instantly), the ACPI controller state has reset properly.

How is your case to work in?

Asus272 said:

How is your case to work in?

Click to expand...

I cleared the CMOS but the problem remains

I was hoping that would work... It's late where you are what would you like to do? We could do the next test or wait until tomorrow.

I'm available tommorow.

You stated in the thread that your bios is current... When was the last update? How long ago did this problem start?