My computer just refused to post at one point. I've been using it for around six months now (GPU much older - maybe a month after launch).
Not OCed. GPU slightly undervolted to keep noise in check. Noctua NH-L9i 17XX cooler.
The board has four diagnostic LEDs. When I hit the power button (one exception I'll list later) the CPU LED turns for, then the RAM LED turns, then the GPU LED turns red, and then the CPU LED turns on immediately as the RAM led switches off and almost immediately does a fade-out kind of switching off (like how a filament bulb will switch off). The exception is if I remove the EPS cable, in which case the CPU LED stays on.
Things I've done so far:
1) Clear CMOS, checked cables, connections, reseated RAM.
2) All parts in place switch on - CPU fan powers up. GPU light powers up, no signals, and then switches off after LED sequence.
3) No GPU switch on - CPU fan powers up, VGA signal, switches off after LED sequence.
4) Flashed BIOS to F6, F11, and F20 versions through Q BIOS Plus with no CPU/RAM in place (renaming the file to gigabyte.bin) and did above steps after flash completion and CPU/RAM installation, same result.
5) Flashed BIOS to F6, F11, and F20 versions through Q BIOS Plus with no RAM just CPU in place (renaming the file to gigabyte.bin) and did above steps after flash completion and CPU/RAM installation, same result.
6) Flashed BIOS to F6, F11, and F20 versions through Q BIOS Plus with CPU/RAM in place (renaming the file to gigabyte.bin) and did above steps after flash completion and CPU/RAM installation, same result.
The exception is when I try boot with EPS cable removed. Then the CPU light just stays on.
What irks me is how the CPU LED trails off instead of switching off. I'm planning on taking the system to check with a different CPU on next working day, but wondering if anyone knows what the issue could be. I've embedded video of 'full system' switch on LED behaviour.
My specs - A 12700K on a Gigabyte Aero G DDR4 running 2x 3600MHz TeamGroup 32GB sticks, and a Gigabyte Vision 3080 (10GB, no LHR), and a Sabrent 2TB PCIE Gen 4 SSD.