My computer now stops during startup with the motherboard's white VGA debug LED illuminated. The system was shut down while I was playing Call of Duty: Modern Warfare III, and since then it will not boot with my dedicated graphics card installed. I have reseated the GPU several times, removed the CMOS battery for about 15–20 minutes, and inspected both ends of the GPU power cable for melting or scorch marks. The connections look normal.
If I connect the monitor to the motherboard's integrated graphics output, the computer boots and runs normally, which makes the RTX 4090 the main suspect. However, I'm wondering whether the problem could instead be the power supply, motherboard, or a damaged PCIe power cable. Event Viewer shows a Kernel-Power event with ID 41 from the unexpected shutdown, although I'm not sure whether that indicates a PSU issue or simply records the crash. The GPU fans were louder during gaming, but not unusually so compared with some of my work software.
My hardware is an ASUS TUF Gaming X670E-PLUS WiFi motherboard with BIOS 1618, a Ryzen 9 7950X, 32GB of Corsair Vengeance RGB DDR5-6000 memory, a Zotac GeForce RTX 4090 24GB, and a Corsair 1200W HX Platinum power supply. I'm waiting to find out whether the graphics card is still covered by the manufacturer's warranty. What troubleshooting steps can help confirm whether the GPU, PSU, cable, or motherboard is at fault?
2 Answers
The white VGA light refers to the motherboard’s diagnostic LEDs that cycle through CPU, RAM, VGA, and BOOT—not a message from the monitor. Since the PC works from the integrated graphics output, the basic system is probably able to POST, but the dedicated card is not being detected or powered correctly. A cable looking undamaged does not prove it is electrically good, so testing with another compatible modular cable is worthwhile; use only a cable designed for that exact PSU. Kernel-Power 41 only records that Windows did not shut down cleanly and does not by itself prove the PSU is failing.
The quickest way to narrow this down is to test the components individually with known-good parts. A VGA debug light can be caused by the graphics card, its power delivery, the motherboard slot, or the PSU, so the symptom alone cannot identify which one failed. If possible, try the 4090 in another compatible system, test another GPU in this system, and try a different PCIe power cable from the PSU. Also confirm that the card is fully seated in the primary PCIe slot and that every required power connector is firmly attached.
I meant the motherboard diagnostic LEDs that cycle through CPU, RAM, VGA, and BOOT. The GPU is installed in the main PCIe slot, and the split PCIe connectors are plugged into the upper sockets nearest the side panel. I do not have a spare power cable to test yet, but I’ll see if I can borrow one or have the card and PSU tested.