Cisco UCS C240 M3 Specifications download pdf (Page 15)

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

CONFIGURING the SERVER

Caveats

■ For optimum performance:

— Populate at least one DIMM per memory channel per CPU

— Do not mix DIMMs with different voltages, frequencies, or types (registered and

unregistered). If you mix 1.35 V and 1.5 V DIMMs, the system defaults to the 1.5 V

mode. If you mix DIMM frequencies, the system defaults to the lower frequency.

■ DIMMs for CPU 1 and CPU 2 (when populated) must always be configured identically.

■ 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 3DPC, 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; all other DIMMs that Cisco offers on this server are

dual-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

— 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 45.

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

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Cisco UCS C240 M3 Specifications Page 15