My desktop stopped reaching POST shortly after two separate events: I shut it down and switched the room's breaker off, then restored power; a few minutes later, my monitors fell and may have tugged on their DisplayPort cables. The monitors still turn on, and I have tested a known-good HDMI cable and a monitor from another room.
The system has an ASUS PRIME B650-PLUS WIFI motherboard, Ryzen 7 9800X3D, Radeon RX 9070 XT, and 64GB of DDR5 memory. The power LED initially blinks quickly, then changes to a steady blink about every two seconds. ASUS documentation identifies that persistent pattern as a VGA detection failure.
The graphics card looked partially unseated. I removed it, and the PCIe retention latch came off but was reattached. With the graphics card removed, I connected the monitor to the motherboard's HDMI output to test the integrated graphics, but the system behaved exactly the same.
So far I have tried several known-good cables and a different monitor, fully discharged the system, cleared CMOS with the CLRTC pins, removed and reinstalled the CMOS battery, tested one RAM stick in slot A2, and successfully used ASUS USB BIOS FlashBack to install BIOS 3881 (A5629.CAP). None of this changed the fast-blink-to-slow-blink behavior or restored video. The GPU is still removed during testing.
What should I check next, and which component is most likely damaged?
3 Answers
At this point, after CMOS resets, a minimal RAM configuration, BIOS FlashBack, and testing without the dedicated GPU, a repair shop is probably the fastest next step. They can test the CPU, board, memory, and power supply individually and inspect the socket and PCIe slot under magnification.
The cable tug may have damaged the PCIe slot or the motherboard around that area, especially if the card was partially pulled out. Inspect the slot, the board for cracks or lifted components, and the CPU socket for bent pins. Testing the graphics card in another compatible system would help separate a GPU fault from a motherboard fault. If the integrated graphics also cannot POST, the motherboard or CPU socket becomes the stronger suspect.
Because the system fails the same way with the graphics card completely removed and the monitor connected to the motherboard, the GPU itself is less likely to be the primary problem. Reseat the RAM carefully and make sure the power supply is fully disconnected from the wall while discharging the system by holding the power button for around 30 seconds.
The motherboard seems like the most likely failure, although I had terrible luck when I tried buying a replacement: the new board arrived with bent CPU-socket pins, and the store was already closed.