I'm building a PC for the first time and performed a pre-build test outside the case. I installed the CPU, motherboard, RAM, SSD, and cooler, then connected the power supply and briefly installed the graphics card. When I switched on the PSU, nothing happened—no motherboard lights, fans, or other signs of power. I reseated the CPU and motherboard power cables and also tried testing with one RAM stick and no GPU, but there was still no response. I performed a paperclip test on the PSU, and its fan spun briefly before stopping. What should I check next, and how can I determine whether the PSU, motherboard connections, or another component is at fault?
3 Answers
The paperclip test isn’t a reliable full test of a power supply. Some PSU fans are designed to spin briefly and then stop, so that behavior can be normal. If the 24-pin and CPU power connectors are definitely correct and shorting the POWER SW pins does nothing, test with a known-good PSU or have the PSU and motherboard checked. Photos of the entire setup and cable connections would also help identify a problem.
The system won’t start just because the PSU switch is turned on. For an outside-the-case test, briefly short the motherboard’s two POWER SW pins with a screwdriver, or connect the case power-switch lead if you’re using one. Double-check the motherboard manual for the exact pins.
Start by checking the basic power connections carefully. The motherboard should have the large 24-pin connector attached, plus the 8-pin CPU power connector near the processor. Make sure both are fully seated and connected to the correct PSU ports. Also inspect the setup for loose connections or anything shorting the board.
Several people asked for photos of the connections. I’ll post clear pictures as soon as I can so the connections can be checked.