Dell R820 owner manual General Memory Module Installation Guidelines, Mode-Specific Guidelines

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/	Operating Frequency (in MT/s)		Maximum DIMM Rank/
	Channel			Channel
		1.5 V	1.35 V
UDIMM ECC	1	1333 and 1066	1066	Dual rank
	2	1333 and 1066	1066	Dual rank
RDIMM	1	1600, 1333, and 1066	1333 and 1066 (Quad	Quad rank
		(Quad rank-1066 max)	rank-800 max)
	2	1600, 1333, and1066	1333 and 1066 (Quad	Quad rank
		(Quad rank-800 max)	rank-800 max)
	3	1066 and 800	Not Applicable	Dual rank
LRDIMM	1	1333 and 1066	1066	Quad rank
	2	1333 and 1066	1066	Quad rank
	3	1066	1066	Quad rank

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.

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