This PC worked normally for nearly a year, but while browsing the system suddenly shut down and restarted. About an hour later, it shut off again and would no longer boot. Pressing the power button makes the PSU click, the fans barely twitch, and the system immediately powers down. Holding the button causes rapid clicking, and after repeated attempts the PSU only clicks again after being switched off and back on.
I reseated every PSU cable on both ends, checked for obvious shorts or burning smells, removed the GPU and other components, tried booting with only the CPU, motherboard, PSU, and one RAM stick, tested the other stick, and cleared the CMOS. I had previously enabled EXPO and applied some CPU undervolting, but resetting the CMOS did not help.
The system uses a Ryzen 7 7800X3D, Noctua L12S cooler, ASRock B650I Lightning motherboard, Corsair SF750 PSU, 32GB of G.Skill Flare X5 memory, a Zotac RTX 5070 Ti, a Fractal Terra case, and a Samsung SSD. Does this sound more like a failed PSU, motherboard, CPU, or another short, and what should I test before RMAing multiple parts?
2 Answers
The fastest way to separate a PSU problem from a motherboard or CPU problem is to test with a known-good PSU, using that PSU's own modular cables. Keep the system to the motherboard, CPU, cooler, one RAM stick, and PSU, with the GPU and SSD disconnected. Since the GPU has already been removed, that rules out one common cause. If a known-good PSU behaves exactly the same way, the motherboard or CPU becomes much more likely. The repeated clicking sounds like the PSU protection circuitry is tripping, but that does not prove the PSU itself is defective.
The earlier EXPO and undervolting settings are worth noting, but clearing CMOS should remove those settings. Ryzen 7000 systems did have earlier problems involving excessive memory-controller or SoC voltage, especially with old firmware and EXPO enabled. Check the motherboard for a standby light, diagnostic LEDs, damaged components, or a loose 8-pin CPU power connector. Also make sure the board is not touching an incorrect case standoff. If the system still instantly trips with a verified PSU and a bare-minimum setup, I would start with the motherboard warranty claim, followed by the CPU if the board tests good.
Voltage-related failures were not limited to one exact CPU model, although the older EXPO/SoC-voltage issue is more relevant to Ryzen 7000 than newer platform reports. A BIOS update may have prevented it, but it cannot help if the board will no longer power on.
I already tried booting without the GPU and got the same result. I’m going to borrow another PSU and test it before sending everything in for warranty service.