HP ProLiant 300-series AMD-based G6 server technology

The AMD Opteron 2400-series processor supports dual memory channels. Two 64-bit-wide memory

channels operate in parallel to provide a 128-bit interface, so memory must be installed in pairs. The

AMD architecture incorporates the following enhancements:

• Write bursting to minimize read/write transitions for greater throughput

• Optimized DRAM paging algorithm for greater throughput

• DRAM prefetcher to intelligently predict and retrieve needed data from main memory

• Core prefetchers that fetch data directly to L1 cache to decrease latency and reduce L2 bandwidth

Double data rate memory

HP ProLiant G6 300-series servers with AMD processors support PC2 Registered double data rate

(DDR-2) DIMMs. These DL 300-series G6 servers use 1-GB, 2-GB, 4-GB, or 8-GB registered DDR-2

DIMMs across 16 DIMM slots. DDR-2 memory devices operate at 1.8V. They use high clock

frequencies to increase data transfer rates and on-die termination control to improve signal quality.

For example, at a clock frequency of 400 MHz, the data transfer rate is 800 MT/s, which translates

to a memory bandwidth of 6400 MB/s per DIMM

Determining memory bus speed

Depending on the quantity and speed of installed DIMMs, memory bus speeds on the DL300-series

G6 servers can be 533-MHz, 667-MHz, or 800-MHz. The memory bus speed is determined by the

BIOS and RBSU using the following two-step process:

Step 1- The BIOS interrogates each DIMM that is installed in the system and sets the memory bus

speed to the least common denominator of the DIMM speeds detected, regardless of the RBSU menu

option selected. For example, with 667-MHz and 800-MHz DIMMs installed, this first step should

complete with the memory bus speed set to 667 MHz regardless of how many DIMMs are installed

on each processor.

Step 2- With this step, the following RBSU menu option settings determine the actual memory bus

speed that is selected.

• Menu Option 1 (Auto default) – Memory bus speed is determined by the number of DIMMs installed

for each processor:

– Auto Case 1: Four or fewer DIMMs = 800-MHz memory bus speed provided that all DIMMs

detected in step 1 are rated for 800 MHz.

– Auto Case 2: Six DIMMs = 667-MHz memory bus speed provided that all DIMMs detected in

step 1 are rated for 667 MHz or greater.

– Auto Case 3: Eight DIMMs = 533-MHz memory bus speed provided that all DIMMs detected in

step 1 are rated for 533 MHz or greater.

• Menu Option 2

– Memory bus speed is set to 533 MHz regardless of how many DIMMs are installed provided that

all DIMMs detected in step 1 are rated for 533 MHz or greater.

Memory management technologies

Memory interleaving on the AMD Opteron 2400-series processors can occur between the processor

memory banks, memory channels, and between processor nodes in a multiprocessor system. All three

For additional information, refer to the HP technology brief titled “Memory technology evolution: an overview of system

memory technologies": http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00256987/c00256987.pdf