General Memory Module Installation Guidelines; Mode-Specific Guidelines - Dell DL4300 Owner's Manual

General memory module installation guidelines

NOTE: Memory configurations that fail to observe these guidelines can prevent your system from
booting, stop responding during memory configuration, or operating with reduced memory.
The 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 installing
memory modules:
• x4 and x8 DRAM based memory modules can be mixed. For more information, see the Mode-specific
guidelines section.
• Up to three dual- or single-rank RDIMMs can be populated per channel.
• 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.
• Populate memory module sockets only if a processor is installed. For single-processor systems,
sockets A1 to A12 are available. For dual-processor systems, sockets A1 to A12 and sockets B1 to B12
are available.
• Populate all the sockets with white release tabs first, followed by the black release tabs, and then the
green release tabs.
• When mixing memory modules with different capacities, populate the sockets with memory modules
with highest capacity first. For example, if you want to mix 4 GB and 8 GB memory modules, populate
8 GB memory modules in the sockets with white release tabs and 4 GB memory modules in the
sockets with black release tabs.
• In a dual-processor configuration, the memory configuration for each processor should 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 capacities can be mixed provided other memory population rules are
followed (for example, 4 GB and 8 GB memory modules can be mixed).
• Mixing of more than two memory module capacities in a system is not supported.
• Populate four memory modules per processor (one DIMM per channel) at a time to maximize
performance.

Mode-specific guidelines

Four memory channels are allocated to each processor. The allowable configurations depend on the
memory mode selected.
Advanced Error Correction Code (lockstep)
Advanced Error Correction Code (ECC) mode extends SDDC from x4 DRAM based DIMMs to both x4 and
x8 DRAMs. This protects against single DRAM chip failures during normal operation.
The installation guidelines for memory modules are as follows:
• Memory modules must be identical in size, speed, and technology.
• DIMMs installed in memory sockets with white release levers must be identical and the same rule
applies for sockets with black release levers. This ensures that identical DIMMs are installed in
matched pair —for example, A1 with A2, A3 with A4, A5 with A6, and so on.
Memory optimized (independent channel) mode
This mode supports Single Device Data Correction (SDDC) only for memory modules that use x4 device
width. It does not impose any specific slot population requirements.
84