Cisco UCS C220 M4 Maintaining The Server page 29

Chapter 3 Maintaining the Server
DIMM Population Rules
Observe the following guidelines when installing or replacing DIMMs:
Observe the following guidelines when installing or replacing DIMMs:
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Each CPU supports four memory channels.
CPU1 supports channels A, B, C, and D.
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– CPU2 supports channels E, F, G, and H.
Each channel has three DIMM sockets (for example, channel A = slots A1, A2, and A3).
– A channel can operate with one, two, or three DIMMs installed.
If a channel has only one DIMM, populate slot 1 first (the blue slot).
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When both CPUs are installed, populate the DIMM sockets of each CPU identically.
Fill blue #1 slots in the channels first: A1, E1, B1, F1, C1, G1, D1, H1
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Fill black #2 slots in the channels second: A2, E2, B2, F2, C2, G2, D2, H2
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Fill white #3 slots in the channels third: A3, E3, B3, F3, C3, G3, D3, H3
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Any DIMM installed in a DIMM socket for which the CPU is absent is not recognized. In a
single-CPU configuration, populate the channels for CPU1 only (A, B, C, D).
Memory mirroring reduces the amount of memory available by 50 percent because only one of the
two populated channels provides data. When memory mirroring is enabled, DIMMs must be
installed in sets of 4, 6, or 8 as described in
Observe the DIMM mixing rules shown in
Installing or Replacing Server Components
Memory Mirroring and RAS, page
Table 3-5.
Cisco UCS C220 M4 Server Installation and Service Guide
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