Datasheet

Cisco UCS C240 M3 High-Density Rack Server (Small Form Factor Disk Drive Model)

CONFIGURING the SERVER

Caveats

■ The server supports 1, 2, or 3 DIMMs per channel for single- or dual-rank RDIMMs.

■ The server supports 1, 2, or 3 DIMMs per channel for quad-rank LRDIMMs.

■ The server supports registered DIMMs (RDIMMs) or load-reduced DIMMS (LRDIMMs), however,

do not mix RDIMMs and LRDIMMs in a server.

■ When using mirroring, DIMMs must be installed in identical pairs across paired DDR3 buses.

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.

■ Memory mirroring reduces the amount of available memory by 50% (quantity of DIMMs must

be even for mirroring).

■ When single- and dual-rank DIMMs are populated for 2DPC, always populate the dual-rank

DIMM in the blue DIMM slot first (blue slot) and the single-rank DIMM last in the black DIMM

slots (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

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:

— The DIMMs are 1600-MHz devices and the DIMM type is RDIMM

— The CPUs chosen support 1600-MHz operation

— There are less than 3 DIMMs per channel

■ With 3 DIMMs populated per channel, memory always runs at 1.5 V regardless if the BIOS

setting is low-power mode (1.35 V) or performance mode (1.5 V).

For more information regarding memory, see CPUs and DIMMs, page 50.

NOTE: Memory speed is limited to 1066 MHz for 3 DPC configurations.

NOTE: 32 GB LRDIMMs run at a maximum speed of 1333 MHz for 1DPC and 2DPC even

though their specified maximum speed is 1600 MHz.