I recently built an AM5 PC using parts I purchased from Micro Center. During the initial test bench at the store, everything worked fine and it POSTed successfully. After bringing it home and putting everything into the case, I encountered a problem when trying to power it on. The power supply clicked once, the fan started spinning, but then it clicked again and shut off immediately. I tried testing it outside the case again with different CPUs and power supplies that are known to work, but the problem persisted. When I remove the 8-pin CPU power cable from the motherboard, the system powers on but gets stuck at the CPU debug light, which seems normal. However, when the 8-pin cable is connected, the motherboard won't even reach the debug lights and shuts down right away. I've already attempted to clear the CMOS to no avail. I checked the CPU pins with my phone camera, and they look fine, though I'm not entirely sure about their condition. I'm considering returning the motherboard for an RMA or exchanging it at the store, but it would take time and cost shipping, plus the store is quite far from me. I'd really like to find a solution to fix the motherboard if possible, as I wanted to gift this PC to my sister soon. I own a multimeter for troubleshooting but don't have a microscope or thermal camera. Any advice would be greatly appreciated!
3 Answers
This sounds more like a case or PSU issue rather than the motherboard itself. Check underneath the 8-pin power connector to see if there's a mounting stud misaligned with a hole in the board. You might also have a faulty or pinched 8-pin cable. Just to be sure, double-check that you're not confusing modular cables from another PSU!
Make sure all standoffs are aligned correctly, and nothing is pinched. Also, verify you're using the right cables from your PSU. It's critical for the system's stability.
When you tested it, did you take it completely out of the case? Sometimes something gets shorted when it’s in the case. If you did pull it out, that's a good start for troubleshooting!
Yes, I pulled it out of the case and tested it on the cardboard the motherboard came in.

I took it out of the case for the test, so it's not a standoff issue. I'm definitely using the correct cable.