Configuring and using DDR3 memory with HP ProLiant Gen8 Servers

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Figure 6. DIMM slots and population order for 12 slot 2P ProLiant Gen8 servers.
Memory system operating speeds
All DDR3 DIMMs for ProLiant Gen8 servers operate natively at either 1600 MT/s or 1333 MT/s. However, the final
operating speed of the memory system for the server depends on the type of DIMMs you install as well as the number of
DIMMs you install per channel. Larger configurations using 2 or 3 DIMMs per memory channel may operate at a slower
speed than the native speed of the DIMMs. Table 9 shows the memory system operating speed for the servers based on
the type and number of DIMMs you install.
Table 9. ProLiant Gen8 server memory operating speeds for different DIMM configurations
RDIMMs
Standard Voltage
(1.5V)
RDIMMs
Low Voltage (1.35V)
LRDIMMs
Low Voltage
(1.35V)
UDIMMs
Low Voltage (1.35V)
1 DIMM per channel 1600 MT/s 1333 MT/s 1333 MT/s 1333 MT/s
2 DIMMs per channel 1600 MT/s 1333 MT/s 1333 MT/s 1333 MT/s
3 DIMMs per channel 1333 MT/s
(with RBSU option)
1066 MT/s 1066 MT/s Not Supported
Mixing DIMM speeds in a configuration is allowed. However, the following will apply.
• The system processor speed rules always override the DIMM capabilities.
• When mixing DIMMs of different speeds, the memory system will use the clock rate of the slowest DIMM in the server.
• Both processors will operate at the same memory clock rate.
General population guidelines
When configuring a 2P ProLiant Gen8 server, you can achieve a good balance between performance, power usage, and
cost by following these general guidelines.
• Populate all channels of each processor (For 2 processor systems, this means populating in groups of 6 or 8 identical
DIMMs).