Cisco UCS C220 M3 User Manual page 17

Caveats
The server supports registered DIMMs (RDIMMs) or load-reduced DIMMS (LRDIMMs), however,
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do not mix RDIMMs and LRDIMMs in a server.
When using mirroring, DIMMs must be installed in identical pairs across paired DDR3 buses.
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That is, mirrored pairs in channels A and B must be identical and pairs in channels C and D
must be identical. However, the DIMMs used in channels A and B and in C and D can be
different.
UDIMMs and non-ECC DIMMs are not supported.
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Memory mirroring reduces the amount of available memory by 50% (quantity of DIMMs must
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be even for mirroring).
When single- and dual-rank DIMMs are populated for 2DPC, always populate the dual rank
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DIMM in the blue DIMM slot, and the single-rank DIMM in the black DIMM slot (only the 4GB
DIMMs are single-rank).
By default, all DIMMs run at 1.35 V, which yields 1333-MHz memory speeds. To run the
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memory DIMMS at 1600 MHz, you need to go into the BIOS or set the policy with UCSM
(service profile) to run in Performance Mode. This forces the DIMMs to operate at 1.5 V and
yields 1600-MHz speeds, provided:
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For more information regarding memory, see
Cisco UCS Cisco UCS C220 M3 High-Density Rack Server (Small Form Factor Disk Drive Model)
The DIMMs are 1600-MHz devices
The CPUs chosen support 1600-MHz operation.
CONFIGURING the SERVER
CPUs and DIMMs, page 48.
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