I'm putting together a PC using mostly new components, with the AIO cooler and graphics card reused from another system. When I press the power button, absolutely nothing happens—no fans twitch, lights come on, or sounds are produced. I've checked that the PSU switch is on, the external power cable is connected, and the internal cables appear to be plugged in. The case uses a single front-panel connector rather than separate tiny power-switch pins. The PSU also works when tested in another PC. What else should I check to find the problem?
3 Answers
Try reducing the build to the minimum needed to power on: motherboard, CPU, cooler, one RAM stick, and the PSU. Disconnect the GPU, storage drives, USB devices, and other accessories. Test each RAM stick individually and try different recommended slots. Also check whether the motherboard needs a BIOS update for the installed CPU, since compatibility can prevent startup, although a total lack of fans or lights more commonly suggests power, wiring, or a faulty board.
A completely dead system often points to the power-button connection. Check the motherboard manual to confirm that the case's combined front-panel plug is positioned correctly on the front-panel header. If needed, briefly short the two power-switch pins with a screwdriver to bypass the case button and see whether the system starts.
Start with the basics again, even if they seem obvious: confirm the wall outlet and power cable work, verify the PSU switch is on, and reseat both ends of every modular PSU cable. Pay particular attention to the motherboard's 24-pin connector and the CPU power connector near the top of the board. Those connectors can look seated while still needing more pressure.
I've checked the cables I thought could cause this, and the PSU is switched on. The PSU also works in my other computer.
The front-panel connections are combined into one plug on this case, and I'm fairly sure it's installed in the right position.