Dell PowerEdge R520 Owner's Manual

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 and RDIMMs 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.
• A maximum of two quad-rank RDIMMs can be populated in a channel.
• A maximum of two single- or dual-rank RDIMMs can be populated in a channel.
• One quad-rank RDIMM and one single- or dual-rank RDIMM can be populated per channel.
• Populate DIMM sockets only if a processor is installed. For single-processor systems, sockets A1 to A6 are available. For dual-processor systems, sockets A1 to A6 and sockets B1 to B6 are available.
• If a processor is installed, install DIMM blanks in the vacant memory sockets assigned to the processor to ensure proper system cooling.
• Populate all sockets with white release tabs first and then black.
• Populate the sockets by highest rank count in the following order - first in sockets with white release levers and then black. For example, if you want 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 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).
• Depending on mode-specific guidelines, populate two or three DIMMs per processor (one DIMM per channel) at a time to maximize performance. For more information, see Mode-Specific Guidelines.
• If memory modules with different speeds are installed, they will operate at the speed of the slowest installed memory module(s) or slower depending on system DIMM configuration.