Memory Subsystem - Compaq dc5850 - Microtower PC Technical Reference Manual

3.3 Memory Subsystem

All models support up to 8 gigabytes of non-ECC PC2-6400 and PC2-5300 DDR2 memory.
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The DDR2 SDRAM "PCxxxx" reference designates bus bandwidth (i.e., a PC2-6400 module
can, operating at a 800-MHz effective speed, provide a throughput of 6400 MBps (8 bytes × 800
MHz)). Memory speed types may be mixed within a system, but the memory controller will
operate at speed of the slowest memory module detected.
The actual clock rate used by the memory will be determined by the processor installed. Memory
in Sempron and Athlon-based systems use a derivative of the CPU clock rate. Memory in
Phenom-based systems run at the specified frequency.
The system board provides four DIMM sockets
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XMM1, channel A (white)
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XMM2, channel B(white)
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XMM3, channel A(black)
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XMM4, channel B (black)
Memory modules do not need to be installed in pairs although installation of pairs (especially
matched sets) provides the best performance. The BIOS will detect the module population and
set the system accordingly as follows:
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Single-channel mode: memory installed for one channel only
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Dual-channel asymetric mode: memory installed for both channels but of unequal channel
capacities.
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Dual-channel interleaved mode (recommended): memory installed for both channels and
offering equal channel capacities, proving the highest performance.
These systems support memory modules with the following parameters:
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Unbuffered, non-ECC 1.8-volt DDR2 DIMMs
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256-Mb, 512-Mb, and 1-Gb memory technologies for x8 and x16 devices
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CAS latency (CL) of 5 for 667- or 800-MHz DDR2, or CL of6 for 800-MHz DDR2
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Single or double-sided DIMMs
An installed mix of memory module types is acceptable but operation will be constrained to the
level of the module with the lowest (slowest) performance.
Technical Reference Guide www.hp.com
Processor/Memory Subsystem
3-3