Technical Product Specification
Intel®
Server Board S2400EP TPS Appendix D: POST Code Diagnostic LED Decoder
Revision 2.0 Intel order number G50763-002
141
POST Memory Initialization MRC Diagnostic Codes
There are two types of POST Diagnostic Codes displayed by the MRC during memory initialization;
Progress Codes and Fatal Error Codes.
The MRC Progress Codes are displays to the Diagnostic LEDs that show the execution point in the MRC
operational path at each step.
Table 68. MRC Progress Codes
Checkpoint
Diagnostic LED Decoder
Description
1 = LED On, 0 = LED Off
Upper Nibble
Lower Nibble
MSB
LSB
8h
4h
2h
1h
8h
4h
2h
1h
LED
#7
#6
#5
#4
#3
#2
#1
#0
MRC Progress Codes
B0h
1
0
1
1
0
0
0
0
Detect DIMM population
B1h
1
0
1
1
0
0
0
1
Set DDR3 frequency
B2h
1
0
1
1
0
0
1
0
Gather remaining SPD data
B3h
1
0
1
1
0
0
1
1
Program registers on the memory controller level
B4h
1
0
1
1
0
1
0
0
Evaluate RAS modes and save rank information
B5h
1
0
1
1
0
1
0
1
Program registers on the channel level
B6h
1
0
1
1
0
1
1
0
Perform the JEDEC defined initialization sequence
B7h
1
0
1
1
0
1
1
1
Train DDR3 ranks
B8h
1
0
1
1
1
0
0
0
Initialize CLTT/OLTT
B9h
1
0
1
1
1
0
0
1
Hardware memory test and init
BAh
1
0
1
1
1
0
1
0
Execute software memory init
BBh
1
0
1
1
1
0
1
1
Program memory map and interleaving
BCh
1
0
1
1
1
1
0
0
Program RAS configuration
BFh
1
0
1
1
1
1
1
1
MRC is done
Memory Initialization at the beginning of POST includes multiple functions, including: discovery, channel
training, validation that the DIMM population is acceptable and functional, initialization of the IMC and
other hardware settings, and initialization of applicable RAS configurations.
When a major memory initialization error occurs and prevents the system from booting with data
integrity, a beep code is generated, the MRC will display a fatal error code on the diagnostic LEDs, and
a system halt command is executed. Fatal MRC error halts do NOT change the state of the System
Status LED, and they do NOT get logged as SEL events. The following table lists all MRC fatal errors
that are displayed to the Diagnostic LEDs.