General Memory Module Installation Guidelines; Mode-Specific Guidelines - Dell PowerEdge R820 Owner's Manual

channel 3: slots D4, D8, and D12
The following table shows the memory populations and operating frequencies for the supported configurations.
DIMM Type DIMMs Populated/
Channel
UDIMM ECC 1
2
RDIMM 1
2
3
LRDIMM 1
2
3

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:
• UDIMMs, RDIMMs, and LRDIMMs must not be mixed.
• x4 and x8 DRAM based DIMMs can be mixed. For more information, see Mode-Specific Guidelines.
• A maximum of two UDIMMs can be populated in a channel.
• 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-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.
• 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.

Mode-Specific Guidelines

Four memory channels are allocated to each processor. The allowable configurations depend on the memory mode
selected.
44
Operating Frequency (in MT/s)
1.5 V
1333 and 1066
1333 and 1066
1600, 1333, and 1066
(Quad rank-1066 max)
1600, 1333, and1066
(Quad rank-800 max)
1066 and 800
1333 and 1066
1333 and 1066
1066
Maximum DIMM Rank/
Channel
1.35 V
1066
1066
1333 and 1066 (Quad
rank-800 max)
1333 and 1066 (Quad
rank-800 max)
Not Applicable
1066
1066
1066
Dual rank
Dual rank
Quad rank
Quad rank
Dual rank
Quad rank
Quad rank
Quad rank