Configuring and using DDR3 memory with HP ProLiant Gen8 Servers

19
Figure 10. Throughput by DIMM Type at 1 and 2 DIMMs per channel
Throughput benefits of two DIMMs per Channel at 1333 MT/s
Although Intel’s design supports two UDIMMs per channel running at 1066 MT/s, HP has engineered ProLiant Gen8
servers to reliability operate at 1333 MT/s with 2 DIMMs per channel when using HP SmartMemory. Enabling 1333 MT/s
operation for two UDIMMs per channel increases throughput by about 22% and decreases loaded latency by 34% over
two DIMMs per channel operating at 1066MHz.
Table 11. Increased throughput with two 4GB 2R LV UDIMMs per channel at 1333 MT/s versus 1066 MT/s
2 DPC @ 1066 MT/s 2DPC@ 1333 MT/s Delta
Throughput (GB/s) 59.55 72.30 22% higher
Idle Latency (ns) 65.34 64.97 .5% lower
Loaded Latency (ns) 196.40 129.20 34% lower
Idle Power (16 DIMM) (W) 2.40 2.40 0%
Loaded Power (16 DIMMs) (W) 30.93 39.57 28% higher
Power benefits of multiple DIMMs per channel at 1.35V
HP has also engineered its DDR3 memory to operate at lower voltage than standard industry memory. HP SmartMemory
RDIMMs can operate at 1.35V at three DIMMs per channel (3 DPC) at 1066 MT/s. Standard RDIMMs must operate at 1.5V
at three DIMMs per channel. As shown in Table 12, 3 DPC operation at 1.35V in a saves almost 20 watts of power in a
fully configured 24 slot server.
Table 12. Lower system power consumption with three 8 GB LV RDIMMs per channel at 1.35V vs. 1.5V operation in a 24 slot HP ProLiant
Gen8 server
3 DPC @ 1.5V 3DPC @ 1.35V Delta
Throughput (GB/s) 60.5 60.5 0%
Idle Power (W) 16.6 15.5 7% lower
Loaded Power (W) 98.6 78.8 20% lower
50
55
60
65
70
75
80
85
90
2R 1333 UDIMM 2R 1333 RDIMM 2R 1600 RDIMM
Throughput (GB/s)
Throughput by DIMM Type
At 1 and 2 DIMMs per channel
1 DIMM / channel
2 DIMMs / channel