A desktop PC that shows no lights, fans, beeps, or display may have a simple external power issue, a switched-off power supply, a loose front-panel button cable, a failed PSU, or a motherboard problem. Rule out the easy causes first.
These steps apply to desktop Windows PCs that appear completely dead. If fans spin but Windows does not load, troubleshoot boot problems instead.
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Use this if pressing the case power button causes absolutely nothing to happen.
Check Power Outside the Case
- Confirm the power cable is firmly plugged into the wall and the back of the PC.
- Test the wall outlet with a lamp or charger.
- Check the power strip or surge protector switch and reset button.
- Look for the PSU rocker switch on the back of the PC and make sure it is set to I, not O.
- Swap the power cable if it looks damaged. Standard desktop power cables are widely interchangeable.
Check Monitor and Video Cables
Sometimes the PC is running but the screen is not showing it.
- Make sure the monitor is powered on.
- Select the correct monitor input.
- Listen for fans, beeps, clicks, or drive noise from the case.
- If the PC has a dedicated graphics card, connect the video cable to the graphics card, not the motherboard video port.
Check Internal Power Connections
Only continue inside a desktop if you are comfortable. Unplug the PC from the wall, ground yourself, and work gently.
- Open the side panel.
- Check the large 24-pin motherboard power cable.
- Check the smaller 4-pin or 8-pin CPU power cable.
- Look for motherboard status LEDs that may light even without display.
- Check the front-panel power button cable on the motherboard pins labeled PWR_SW or POWER SW.
- If recent hardware was added, disconnect it and test again in case it caused a short or seating problem.
Power Supply and Motherboard Notes
If external power and internal cables are correct, the power supply is the next suspect. Paperclip PSU testing involves live electrical hardware and should be done only with a dedicated safe guide or by a repair shop. If the PSU tests good and the PC remains dead, the motherboard is the likely next failure point.
Sources
- Dell Support: Computer does not power on
- HP Support: Desktop computer will not turn on
- Corsair: Power supply troubleshooting guide