Lenovo System x3650 M4 HD, Installation And Service Manual

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• When you use memory mirrored channel, you must install a pair of DIMMs at a time. The two DIMMs in
each pair must be identical in size, type, and rank (single, dual, or quad), and organization, but not in
speed. The channels run at the speed of the slowest DIMM in any of the channels.
• The maximum available memory is reduced to half of the installed memory when memory mirrored
channel is enabled. For example, if you install 64 GB of memory using RDIMMs, only 32 GB of
addressable memory is available when you use memory mirrored channel.
• For UDIMMs, DIMM connectors 3, 6, 7, and 10 for microprocessor 1 and DIMM connectors 15, 18, 19,
and 22 for microprocessor 2 are not used in memory mirrored channel mode.
The following diagram lists the DIMM connectors on each memory channel.
Figure 32. Connectors on each memory channel
The following table shows the installation sequence for memory mirrored channel mode:
Table 8. Memory mirrored channel mode DIMM population sequence
Number of DIMMs
Number of installed
microprocessor
DIMM connector
First pair of DIMMs 1 1, 4
Second pair of DIMMs 1 9, 12
Third pair of DIMMs 1 2, 5
Fourth pair of DIMMs 1 8, 11
Fifth pair of DIMMs 1 3, 6
Sixth pair of DIMMs 1 7, 10
Seventh pair of DIMMs 2 13, 16
Eighth pair of DIMMs 2 21, 24
Ninth pair of DIMMs 2 14, 17
Tenth pair of DIMMs 2 20, 23
Eleventh pair of DIMMs 2 15, 18
Twelfth pair of DIMMs 2 19, 22
Note: DIMM connectors 3, 6, 7, 10, 15, 18, 19, and 22 are not used in memory mirrored channel mode when UDIMMs
are installed in the server.
Memory rank sparing
The memory rank sparing feature disables the failed memory from the system configuration and activates a
rank sparing DIMM to replace the failed active DIMM.
Chapter 2
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Installing optional devices
47