I built this PC about a year ago, and it suddenly powered off while I was using it. Now, when I press the power button, the power supply clicks off almost immediately and the motherboard's CPU indicator flashes red. A few days earlier, the system had started lagging, so I ran disk cleanup and removed around 12 GB of files, though I'm not sure whether that is related. The system uses a Gigabyte B650 Gaming X AX motherboard, Ryzen 7 7800X3D processor, Radeon RX 9070 XT 16GB graphics card, Montech Century II power supply, Klevv CRAS C910 2TB SSD, 32GB Silicon Power DDR5 memory, Thermalright Royal Knight 120 SE cooler, and an NZXT H5 Flow case. I have already reseated the cables, cleared CMOS, removed and reinstalled the battery, and checked for obvious bent pins, but the problem remains.
3 Answers
The earlier lagging may point to heat or unstable power, but deleting files during disk cleanup would not cause this kind of immediate hardware shutdown. Inspect the CPU and socket for paste contamination, scorch marks, or damaged pins, and remount the cooler evenly without overtightening it. Avoid repeatedly pressing the power button while the PSU is tripping; isolate the fault methodically instead.
The disk cleanup is almost certainly unrelated. A power supply clicking off while the CPU light flashes usually points to a protection shutdown caused by a short, power-delivery problem, or a failed component. Reseat the 24-pin motherboard cable and the 8-pin CPU cable, then test with the GPU and drives disconnected. Use only one RAM stick in the second slot from the CPU, and try each stick separately. Since the 7800X3D has integrated graphics, the system can be tested without the dedicated GPU. Also inspect the CPU socket and make sure the cooler has not been tightened excessively. If it still shuts off instantly with only the CPU, cooler, one RAM stick, and power cables connected, test with a known-good PSU or have a repair shop check the board and power supply.
The flashing light is an error indicator, so check the motherboard manual for the exact diagnostic sequence. The power supply switching itself off suggests it is detecting over-current or a short rather than this being a software issue. Try the system outside the case with the minimum hardware installed, then add components back one at a time. If the minimum setup still trips the PSU, the likely causes are the PSU, motherboard VRM, CPU, or a socket/contact problem.
If the graphics card uses multiple power connectors, run separate cables from the PSU for each connector instead of using one daisy-chained cable. That is worth checking once the minimum-boot test is complete.
I reseated all the cables, cleared CMOS, removed the battery, and checked for bent pins, but it still clicks off the same way.