IBM System x3650 Type 7979 Problem Determination And Service Manual page 133

v 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 Table 8 for the DIMM
connectors that are in each group.
Table 8. Memory mirroring DIMM installation sequence
Group DIMM connectors
1 1, 4, 7, and 10
2 2, 5, 8, and 11
3 3, 6, 9, and 12
Table 9. Memory mirroring DIMM functions
Group Active DIMMs
1 1, 4
2 2, 5
3 3, 6
v Three online-spare memory configurations are supported. The online-spare
DIMM pairs must be the same speed, type, and the same size as, or larger than,
the largest active DIMM pairs. See Table 10 on page 116 for the online-spare
DIMM connector assignments.
DIMM 12
Channel 3
DIMM 11
DIMM 10
Branch 1
DIMM 9
DIMM 8
Channel 2
DIMM 7
DIMM 6
Channel 1
DIMM 5
DIMM 4
Branch 0
DIMM 3
Channel 0
DIMM 2
DIMM 1
Mirroring DIMMs
7, 10
8, 11
9, 12
Chapter 4. Removing and replacing server components
115