I built this PC a little over a year ago. Yesterday, it was powered on but completely unresponsive. The case power button did nothing, so I switched off the power supply. After that, the system would not turn back on at all. I checked the case switch, tried the motherboard's onboard power button, and even swapped in another power supply, but there was still no response. I'm not sure what to test next. The system has an RTX 5070, Core i7-14700K, and DDR5 memory. The motherboard is listed as an ASUS ROG Strix X470-F, although that model would not be compatible with the processor or DDR5, so the exact motherboard model may need to be confirmed.
3 Answers
Disconnect the case front-panel connectors and start the system using the motherboard’s onboard power button, which you already tried. You can also test it outside the case with only the CPU, one RAM stick, and basic graphics output connected. Inspect for a short, loose screw, damaged connector, or signs of burning. If it remains completely dead with a confirmed-working PSU, the motherboard or CPU may have failed.
Double-check the motherboard model before troubleshooting further. An X470-F uses the AM4 socket and DDR4 memory, so it cannot run an i7-14700K or DDR5. If the board is actually a Z790 or another LGA1700 DDR5 model, check its diagnostic LEDs or display for a fault code. If it really is an X470-F, the listed parts could not have been operating together as described.
If absolutely nothing happens—not even motherboard LEDs, fans, or a brief power attempt—the likely causes are the power supply, motherboard, or a power connection. Reseat the 24-pin motherboard cable, CPU EPS cable, GPU power cable, and the PSU-side connections if it’s modular. Also verify the wall outlet, power cable, and PSU switch. Since you already tried another PSU, the motherboard becomes a stronger possibility, assuming the replacement PSU is known-good and powerful enough.

Related Questions
Lenovo Thinkpad Stuck In Update Loop Install FilterDriverU2_Reload