Asus Maximus IV Extreme-Z - Manual (Page 56)

9. Debug LEDs
The Debug LED design provides you the 2-digit display, allowing you to know
the system status. Refer to the Debug table below for details.
Debug table
Code Description
00 Not used
01 Power on. Reset type detection (soft/hard).
02 AP initialization before microcode loading
03 System Agent initialization before microcode loading
04 PCH initialization before microcode loading
05 OEM initialization before microcode loading
06 Microcode loading
07 AP initialization after microcode loading
08 System Agent initialization after microcode loading
09 PCH initialization after microcode loading
0A OEM initialization after microcode loading
0B Cache initialization
0C – 0D Reserved for future AMI SEC error codes
0E Microcode not found
0F Microcode not loaded
10 PEI Core is started
11 – 14 Pre-memory CPU initialization is started
15 – 18 Pre-memory System Agent initialization is started
19 – 1C Pre-memory PCH initialization is started
2-24 Chapter 2: Hardware information