Cisco UCS C22 User Manual

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Cisco UCS C22 Server Installation and Service Guide
OL-26646-01
Chapter 3 Maintaining the Server
Installing or Replacing Server Components
DIMM Population Rules
Observe the following guidelines when installing or replacing DIMMs:
• Each CPU supports three memory channels.
– CPU1 supports channels A, B, and C.
– CPU2 supports channels D, E, and F
• Each channel has two DIMM slots (for example, channel A = slots A0 and A1).
– A channel can operate with one or two DIMMs installed.
– If a channel has only one DIMM, populate slot 0 first (the blue slot).
• 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
• In a single-CPU configuration, populate the channels for CPU1 only. Any DIMM installed in a
DIMM socket for which the CPU is absent is not recognized.
• 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 “
Enabling
Low-Voltage DIMM Operation.”) A 1600 MHz DIMM set to Power Savings Mode operates at
1066 MHz.
• Observe the DIMM mixing rules shown in Table 3-3.
• Memory mirroring reduces the amount of memory available by 50% because only one of the two
populated channels provides data. When memory mirroring is enabled, DIMMs must be installed in
sets of 2 or 4, as described in
Memory Mirroring, page 3-20.
Ta b l e 3-3 DIMM Mixing Rules
DIMM Parameter Mixed Mix Across Single Channel? Mix Across Multiple Channels?
DIMM size (4, 8, 16 GB) No—Must be same size in
channel.
Yes—Can be different sizes in server.
DIMM speed (1333 or
1600 MHz)
No—Must be same speed in 
channel.
No—Must be the same speed in server.
DIMM type (R-DIMM) No—Must be same type in
channel.
No—Must be the same type in server.

Cisco UCS C22 Specifications

General

Brand	Cisco
Model	UCS C22
Category	Server
Language	English