Your desktop PC will not turn on, restarts under load, or shuts off randomly, and you want to test the power supply before replacing parts. This guide applies to standard ATX desktop PSUs, not laptop chargers or sealed laptop internals.
Does This Affect You?
The paperclip test is a common first check that tells you whether a PSU can turn on when triggered outside the PC. It does not prove the voltages are stable under real load, but it helps separate a completely dead PSU from other startup problems.
Unplug the PC, disconnect the PSU from every component, and test the PSU by itself. Do not test a unit that smells burnt, has scorch marks, or shows damaged components. Keep fingers and tools away from the fan and connectors once power is connected. These steps are at your own risk; when unsure, replace the PSU or ask a repair shop.
The Paperclip Test
This takes only a few minutes after the PSU is isolated.
- With the PC unplugged, disconnect the large 24-pin motherboard connector and all PSU cables from internal components.
- Straighten one end of a standard paperclip.
- On the 24-pin connector, bridge the green wire pin to any black ground wire pin. If your cable colors are not visible, use the PSU manual pinout.
- Plug the PSU into the wall and switch the rear power switch on. Do not touch the connector while powered.
- If the PSU fan spins and stays running, the PSU turns on.
- If nothing happens, the PSU has likely failed.
- Switch the PSU off, unplug it, and remove the paperclip before reconnecting anything.
Some modern PSUs have zero-RPM fan modes, so a fan may spin briefly and stop or may not be a perfect indicator on every model. A dedicated PSU tester or multimeter gives better information, but the paperclip test remains a useful first step.
A PSU can pass this test and still fail under load. Random restarts during gaming, rendering, or other heavy work can come from unstable voltage, an undersized PSU, or a failing unit that only misbehaves when stressed. Compare the PSU rated wattage and connectors with your GPU and CPU requirements.
A multimeter can measure ATX voltages more directly, but that is a more advanced test and still may not fully simulate real load. Power supplies are not normally worth internal repair. If the paperclip test fails or measured voltages are out of tolerance, replacement is the standard path.
Sources
- Corsair – How to test a PSU with the paperclip method (2024)
- EVGA Support – Power supply troubleshooting guide (2025)
- Intel Support – Troubleshooting a computer that will not boot (2025)