System fails to update or display after reboot.
System fails to update or display after reboot.
You're experiencing unusual behavior with your system. It seems like the keyboard and mouse stopped responding after a power cycle, and upon restarting, the screen displayed black with a flashing underline before showing a boot message. The CPU and GPU temperatures appear normal, and you've tried several hard restarts. The motherboard's CPU boot light stayed on. You mentioned checking the case orientation—booting works when the PC is lying flat but not when it's upright. This could indicate an issue with the socket connection or power delivery. It might be worth investigating the physical connections in the CPU socket and ensuring proper ventilation and cooling.
It seems there might be a mechanical issue. I’d inspect to ensure everything is securely fastened. Check CPU socket, DIMM slots, PCIe connections, and other mainboard components.