My PC was working normally until today, when the display stopped responding and it would not wake from sleep after moving the mouse or using the keyboard. Holding the power button eventually turned it off, but it would not start properly afterward. I tried cycling the PSU and wall power, switching HDMI from the graphics card to the motherboard's integrated graphics output, clearing the CMOS, unplugging the system, and holding the power button to discharge it. None of this helped.
The motherboard's CPU debug LED stays red continuously, while the DRAM, VGA, and storage LEDs remain off. The system was built in April 2025 and had worked reliably until now. Could this indicate a failed CPU or motherboard, and what troubleshooting should I try before pursuing an RMA? I do not have a spare CPU or motherboard for testing.
Specs: Ryzen 9 9950X3D, ASRock B850 Steel Legend WiFi, XFX Radeon RX 9070 XT, 64GB Corsair Vengeance DDR5-5200 (2x32GB), Corsair RM1000e 1000W PSU, and a 2TB Samsung 990 Pro NVMe SSD.
1 Answer
Try booting with only one memory module installed. Remove both sticks, install one in a recommended DIMM slot, and try to POST. If nothing changes, move that same stick through the other slots, then repeat the process with the second stick. Even though the DRAM light is off, a memory-training or contact problem can still prevent startup. Also make sure the CPU power connector and motherboard power cable are fully seated, and reseat the memory and CPU if you are comfortable doing so.
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