I'm building a PC for the first time and tried testing the components outside the case before installing everything. I mounted the CPU, RAM, SSD, and CPU cooler, then connected the GPU and power supply. When I switched on the PSU, nothing happened—no motherboard lights, fans, or other signs of life. I reseated the CPU and motherboard power cables several times, then tried booting with a single RAM stick and no GPU, but still got no response. I also performed a paperclip test on the PSU; its fan spun briefly and stopped, though I now understand that this test doesn't reliably confirm whether a PSU is working. What should I check next before assuming one of these expensive parts is defective?
4 Answers
Make sure both main motherboard power connections are fully seated: the large 24-pin connector and the 8-pin CPU power connector near the processor. They can look connected while still needing a firm push. If there are absolutely no fans, lights, or diagnostic LEDs, the PSU, power connections, or motherboard are the main things to investigate. Photos of the setup and connectors would make it much easier to spot a problem.
For a test outside the case, the system usually won’t start from the case’s power button because that button isn’t connected yet. Briefly bridge the two motherboard power-switch pins with a screwdriver or another conductive metal object. Check the motherboard manual to identify the correct pins, and only touch those two pins momentarily.
The paperclip test only shows that the PSU can start its fan circuit, and many modern PSU fans deliberately stop when the unit is cool. It doesn’t prove that the PSU can deliver stable power under load. Double-check that the PSU is switched on, the wall outlet and power cable work, and that you’re using the correct modular cables supplied with that exact PSU.
Try a minimal setup: motherboard on its box, CPU and cooler installed, one RAM stick in the recommended slot, the 24-pin and CPU power cables connected, and no SSD or GPU initially. Clear the CMOS if the manual explains how, then try starting it by bridging the power pins. If there is still no response at all, test with a known-good PSU or contact the retailer for component diagnostics rather than repeatedly reconnecting parts.
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