User`s guide

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5: Advanced Serverboard Setup
Memory DIMM Rules
Use the following rules when installing memory DIMMs:
• Minimum Number of DIMMs—A minimum of one DIMM on each processor must always
be installed.
• Slot Order—For each memory channel, populate the DIMM slot that is furthest from the
processor first.
• Channel Balancing—For best performance, populate each channel with the same number
of identical DIMMs.
• Mixing DIMM Speeds—All DIMMs populated on all channels on both processors should
be able to support the highest frequency, because the timings of the slowest DIMM will be
applied to all DIMMs.
• Mixing DIMM Sizes—When mixing DIMMs on a channel that have a mixed number of
ranks, it is recommended to have the total number of ranks on the channel be even to avoid
bandwidth degradation. Example: placing a single-rank DIMM and a dual-rank DIMM on
the same channel is not desirable. The total number of ranks would be three, an odd number
of ranks. If mixing is unavoidable, then DIMMs with the most ranks need to be populated in
the slots farthest from the processor (the “A” slots).
• Maximum Memory Performance —The DIMMs within a node must be identical in speed
and rank:
– Speed—1066 or 1333 M transfers/sec (MT/s)
– Number of ranks —1, 2, or 4
• Single-processor Node Board
Only Processor 2 is installed in a single processor node board. Only install DIMMs in the P2
DIMM slots. Follow the Processor 2 section of Table 5-1 and Table 5-2 for installing
DIMMs.
• Minimum Compute Blade Memory Size:
There is 4GB compute blade minimum in systems running SGI Management Center
software.