HP ProLiant DL380p DDR3 memory technology - Page 3

Table 1. DDR3 memory speeds JEDEC Name PC3 - 12800 PC3 - 10600 PC3 - 8500 PC3 - 6400 Common Name DDR3-1600 DDR3-1333 DDR3-1066 DDR3- 800 Data Transfer Rate 1600MT/s 1333 MT/s 1066 MT/s 800 MT/s Maximum DIMM Throughput 12.8GB/s 10.6 GB/s 8.5 GB/s 6.4 GB/s The faster data rates for DDR3 result in maximum possible throughput rates that are significantly greater that those of DDR2. The maximum bandwidth represents the amount of data that can be moved between a memory controller and the DIMMs if data is transferred on every transfer cycle. With DDR3-1333 memory, the maximum bandwidth per memory channel is 10.6 GB/s. Memory power consumption DDR3 is designed to be more power efficient than DDR2. DDR3 DIMMs operate at 1.5V compared to the 1.8V for DDR2 memory. DDR-3 also provides for low-voltage DIMMs that will operate at 1.35V, further lowering power consumption. Figure 1 shows the idle and loaded power consumption for a 12 DIMM DDR3 memory configuration at different memory speeds. Figure 1. Power consumption by memory speed (using twelve 4GB dual rank RDIMMs) 140 DDR-3 800 120 DDR-3 1066 DDR-3 1333 100 Power (Watts) 80 60 40 20 0 Idle Power (W) Loaded Power (W) DDR3 memory running at 1333 MT/s uses about 25% more power than the same memory running at 800 MT/s. As a general guideline, DDR3 memory uses about 30% less power than DDR2 memory when running at the same speed (800 MT/s). At 1333 MT/s, DDR3 uses about the same power as DDR2 memory while providing an improvement in maximum bandwidth. DDR3 also features two power savings modes that the memory controller can employ to further reduce memory power consumption - CKE power down and self-refresh mode. With CKE power down, the memory controller performs a look ahead at the queue of pending memory operations. If none are scheduled for a particular DIMM, then it is placed in a lower power state and only re-awakened for refreshes. For additional power savings, the memory controller will place the DRAMs in self-refresh 3