IBM x3550 Problem Determination And Service Manual page 73

Figure 1. DIMM connectors, channels, and branches
v Each DIMM in a pair must be the same size, speed, type, and technology to
v You can configure the server to use memory mirroring. Memory mirroring stores
Table 7. DIMM installation sequence (continued)
Pair DIMM connectors
4 6 and 8
ensure that the server will operate correctly.
data in two pairs of DIMMs simultaneously. If a failure occurs, the memory
controller switches from the active pair to the mirroring pair. Memory mirroring
reduces the amount of available memory. Enable memory mirroring through the
Configuration/Setup Utility program.
When you use memory mirroring, you must install two pairs of DIMMs at a time.
The four DIMMs in each group must be identical. See the following table for the
installation sequence of DIMM connectors for memory mirroring.
Table 8. Memory mirroring DIMM installation sequence
Group DIMM connectors
1 1, 3, 5, and 7
2 2, 4, 6, and 8
Channel 2
Channel 3
DIMM 5 connector
DIMM 6 connector
Branch 1
DIMM 7 connector
DIMM 8 connector
DIMM 1 connector
DIMM 2 connector
DIMM 3 connector
DIMM 4 connector
Branch 0
Channel 1
Channel 0
Chapter 4. Removing and replacing server components
55