I'm troubleshooting a newly assembled PC with a Ryzen 5 5500X3D, MSI MAG B550M BAZOOKA motherboard, 16GB of Corsair Vengeance LPX DDR4-3200, a PowerColor RX 6700 Fighter OC, Corsair CX650M power supply, Solidigm P44 Pro 1TB SSD, and a Thermalright Assassin King 120 SE cooler in a Lian Li A3-mATX case. The system powers on, the fans and RGB work, but there is no display and the motherboard's CPU debug light stays lit. I tried clearing the CMOS, booting with only the essential components installed, and using the USB BIOS flash button several times, but the flashing process never seemed to finish. The same motherboard and CPU were working normally a few days earlier. The only changes were the CPU cooler and SSD, and the parts were transported between locations before the problem appeared. What should I check, and is the motherboard likely damaged?
3 Answers
Try a complete CMOS reset: disconnect power, remove the CMOS battery, and short the clear-CMOS pins according to the motherboard manual. Then reinstall the battery and test with one memory stick, the CPU, cooler, and graphics card. If that still produces the same CPU light, the motherboard becomes the main suspect.
If the CPU and all the other parts were confirmed working before transport, physical damage to the board during transit is plausible. Once the socket, CPU seating, power connections, and CMOS reset have been checked, swapping in a known-good motherboard is the most practical test. In this case, replacing the motherboard appears to have been the agreed next step.
The previous owner looked over the system with me, and we concluded that the motherboard probably failed during transport. He’s going to provide a replacement board.
Since the system worked before it was moved and the cooler and SSD were changed, start by checking the CPU installation. Remove the cooler and CPU, inspect the socket carefully for bent or damaged pins, and reseat the processor. Also make sure the cooler isn’t mounted with excessive pressure. A CPU debug light can be caused by a socket, seating, or motherboard problem rather than the processor itself.
I already removed the battery and shorted the clear-CMOS pins, then left the battery out overnight. I’m going to reinstall it and test the system again from scratch.