ASUS Q-LED and Q-Code Motherboard Debug Diagnostic Guide
Diagnose ASUS motherboard failures using 4-color Q-LED status lights (CPU, DRAM, VGA, BOOT) and 2-digit alphanumeric Q-Code hexadecimal readouts.
Internal desktop parts run on harmless 12V DC voltage and cannot shock you. Simply unplug the wall power cable first, then touch the unpainted metal case frame to ground static electricity.
Common Symptoms & Tells
- System fails to complete
- Q-LED stays lit on Red (CPU), Yellow (DRAM), White (VGA), or Yellow-Green (BOOT)
- 2-digit Q-Code LED displays codes 00, 55, d6, or 99
Interactive Fix Checklist
0 of 4 steps completedDecode Q-LED color indicator
Observe the four color LEDs adjacent to the 24-pin ATX connector. Red indicates CPU failure or missing 8-pin EPS 12V connection; Yellow indicates DRAM memory training failure; White indicates VGA handshake failure; Yellow-Green indicates no bootable OS device found.
Decode 2-digit Q-Code readout
If your board includes a 7-segment display, read the hex code. Code 00 indicates CPU not detected or seated incorrectly; Code 55 indicates memory not detected; Code d6 indicates no console output device (); Code 99 indicates Super I/O or PCIe initialization halt.
Clear CMOS and reset memory profiles
Shut down PC, unplug AC power cord, and press the Clear rear I/O button for 5 seconds (or bridge the 2-pin CLRTC header with a screwdriver) to wipe unstable DOCP, EXPO, or memory timings.
Isolate memory to slot A2
Remove all sticks except a single module in primary DIMM slot A2 (second slot away from CPU). Power on and allow up to 3 minutes for initial DDR5 memory training to complete.
Still having trouble with your PC?
Describe what is happening to your AI Technician. We will tailor the fix to your exact hardware setup.