Cisco UCS C24 Installation And Service Manual page 55

Chapter 3 Maintaining the Server
Figure 3-11
DIMM Population Rules
Observe the following guidelines when installing or replacing DIMMs:
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DIMM Slots and CPUs
A0
A1
B0
B1
C0
C1
CPU1
D0
D1
E0
E1
F0
F1
CPU2
Each CPU supports three memory channels.
CPU1 supports channels A, B, and C.
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CPU2 supports channels D, E, and F
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Each channel has two DIMM slots (for example, channel A = slots A0 and A1).
A channel can operate with one or two DIMMs installed.
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If a channel has only one DIMM, populate slot 0 first (the blue slot).
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When both CPUs are installed, populate the DIMM slots of each CPU identically.
– Fill blue slots in the channels first: A0, D0, B0, E0, C0, F0
– Fill black slots in the channels second: A1, D1, B1, E1, C1, F1
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.
Although 1600 MHz DIMMs can be run in Power Savings Mode (1.35 V operation), 1600 MHz
operation is supported only when the DDR mode is set to Performance Mode (see
Low-Voltage DIMM Operation.") A 1600 MHz DIMM set to Power Savings Mode operates at
1066 MHz.
Observe the DIMM mixing rules shown in
Installing or Replacing Server Components
Table 3-3.
Cisco UCS C24 Server Installation and Service Guide
"Enabling
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