ATX 24-Pin Power Sequence and PS_ON Green Wire Triage
Test ATX power supply startup sequences using the paperclip green wire PS_ON jump test and verify primary +12V, +5V, and +3.3V DC rail delivery.
Internal desktop parts run on harmless 12V DC voltage and cannot shock you. Simply unplug the wall power cable first, then touch the unpainted metal case frame to ground static electricity.
Common Symptoms & Tells
- PC does not respond at all when pressing the front power button
- Zero lights, zero fan movement, and zero acoustic clicks from
- Suspected dead power supply, blown fuse, or broken front panel switch
Interactive Fix Checklist
0 of 4 steps completedDisconnect power and unplug 24-pin connector
Turn off the rocker switch and unplug the AC wall cable. Unplug the 24-pin main motherboard power connector and all internal power cables.
Perform paperclip PS_ON jump test
Locate Pin 16 PS_ON# (green wire on standard ATX cables) and any adjacent COM ground pin (black wire, Pins 15, 17, or 18). Bend a metal paperclip and insert ends into Pin 16 and Pin 17.
Connect minimum load and power on
Connect a single 12V case fan or old SATA drive to provide minimum load. Plug AC cord in and flip rocker switch to ON. If fan spins, the power supply turns on correctly.
Measure DC rail voltages with multimeter
Using a digital multimeter, check yellow wires for +12V DC, red wires for +5V DC, orange wires for +3.3V DC, and purple wire for +5VSB standby voltage. Replace if voltages fall below 5% tolerance.
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