68 Installing System Components
• Single-rank, and dual-rank RDIMMs of sizes 1 GB, 2 GB, 4GB, and 8
GB are supported for a total of up to 144 GB.
• Quad-rank RDIMMs (two per channel) are supported for a total of
upto 48 GB.
General Memory Module InstallationGuidelines
To ensure optimal performance of your system, observe the following general
guidelines when configuring your system memory.
NOTE: Memory configurations that fail to observe these guidelines can prevent
your system from starting and producing any video output.
• Except for memory channels that are unused, all populated memory
channels must have identical configurations.
• The memory configuration for each processor must be identical.
• Memory modules of different sizes can be mixed in A1–A4 or B1–B4
(forexample, 2 GB and 4 GB), but all populated channels must have
identical configurations.
• For optimizer mode, memory modules are installed in the numeric order of
the sockets beginning with A1 or B1.
• For memory mirroring or advanced ECC mode, the channel furthest from
the processor is unused and memory modules are installed beginning with
channel A1 or B1 and proceeding with channel A2 or B2.
• Advanced ECC mode requires memory modules that use x4 or x8 DRAM
device widths.
• 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 support up to 1066 MHz.
• Three memory modules per channel support up to 800 MHz,
regardless of memory module speed.
– For quad-rank memory modules:
• One memory module per channel supports up to 1066 MHz.
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