Dell EMC PowerEdge M640 Installation and Service Manual

Your 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:

• LRDIMMs, and RDIMMs must not be mixed.
• x4 and x8 DRAM based DIMMs can be mixed. For more information, see the Mode-specific guidelines section.
• A maximum of two different ranked DIMMs can be populated in a channel.
• 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 DIMM sockets only if a processor is installed. For single-processor systems, sockets A1 to A8 are available. For dual-processor systems, sockets A1 to A8 and sockets B1 to B8 are available.
• Populate the sockets by highest capacity DIMM in the following order - first in sockets with white release levers and then black. For example, if you want to mix 16 GB and 8 GB DIMMs, populate 16 GB DIMMs in the sockets with white release tabs and 8 GB 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, 4 GB and 8 GB memory modules can be mixed).
• Depending on mode-specific guidelines, populate six DIMMs per processor (one DIMM per channel) at a time to maximize performance. For more information, see the Mode-specific guidelines section.