Dell DR4000 - Manual (Page 77)

Installing System Components 77
• The memory speed of each channel depends on the
memory configuration:
–
For single or dual-rank memory modules:
• One memory module per channel supports up to 1333 MHz.
• Two memory modules per channel supports up to 1067 MHz.
– For quad-rank memory modules:
• One memory module per channel supports up to 1067 MHz.
• Two memory modules per channel are limited to 800 MHz,
regardless of memory module speed.
• If quad-rank memory modules are mixed with single- or dual-rank
modules, the quad-rank modules must be installed in the sockets
with the white release levers.
• If memory modules with different speeds are installed, they operate at the
speed of the slowest installed memory module(s).
Mode-Specific Guidelines
Three memory channels are allocated to each processor. The number of
channels used and the allowable configurations depend on the memory mode
selected.
Advanced ECC (Lockstep) Mode Support
In this configuration, the two channels closest to the processor are combined
to form one 128-bit channel. This mode supports Single Device Data
Correction (SDDC) for both x4- and x8-based memory modules. Memory
modules must be identical in size, speed, and technology in
corresponding slots.
Memory Mirroring Support
The system supports memory mirroring if identical memory modules are
installed in the two channels closest to the processor (memory should not be
installed in the farthest channel). Mirroring must be enabled in the System
Setup program. In a mirrored configuration, the total available system
memory is one-half of the total installed physical memory.
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