General Memory Module Installation Guidelines - Dell PowerEdge M820 Owner's Manual

Processor DIMM
Type Type

General Memory Module Installation Guidelines

This system supports Flexible Memory Configuration, enabling the system to be configured and run in
any valid chipset architectural configuration. The following are the recommended guidelines for best
performance:
• RDIMMs and LRDIMMs must not be mixed.
• x4 and x8 DRAM based DIMMs can be mixed. For more information, see Mode-Specific Guidelines.
• Up to two quad-rank RDIMMs and up to three dual- or single-rank RDIMMs can be populated per
channel.
• Up to three LRDIMMs can be populated regardless of rank count.
• Populate DIMM sockets only if a processor is installed. For dual-processor systems, sockets A1 to A12
and B1 to B12 are available. For four-processor systems, sockets A1 to A12, B1 to B12, C1 to C12, and
D1 to D12 are available.
• Populate the sockets by highest rank count in the following order - first in sockets with white release
levers, then black, and then green. For example, to mix quad-rank and dual-rank DIMMs, populate
quad-rank DIMMs in the sockets with white release tabs and dual-rank DIMMs in the sockets with
black release tabs.
• In a dual- or four-processor configuration, the memory configuration for each processor must be
identical. For example, if you populate socket A1 for processor 1, then you must populate socket B1
for processor 2, and so on.
• Memory modules of different sizes can be mixed provided that other memory population rules are
followed (for example, 2 GB and 4 GB memory modules can be mixed).
• Populate four DIMMs per processor (one DIMM per channel) at a time to maximize performance.
• If memory modules with different speeds are installed, they operate at the speed of the slowest
installed memory module(s) or slower depending on system DIMM configuration.
• Populate DIMMs based on the following processor-heat sink configurations.
DIMMs Operating Frequency (in MT/s)
Populated/
Channel
1.5 V
1600,1333, and
1066
2 1600,1333, and
1066
1333 and 1066
3 1333 and 1066
1066
Maximum DIMM
Rank/Channel
1.35 V
Octal rank
1600,1333, and Quad rank
1066
Octal rank
1066 Quad rank
Octal Rank
55