HP ML150 HP ProLiant G6 Technology Overview - Page 4

Integrated memory controller One of the most notable improvements in Intel Xeon 5500 series processors is the integrated memory controller. The memory controller uses three channels (up to 1333-MHz each) to access dedicated DDR-3 memory sockets. This delivers a big performance improvement over previous architectures that provide only two memory channels and require processors to share a single pool of system memory. The three memory channels have a total bandwidth of 32 GB/s. Three-level cache hierarchy Each Intel Xeon 5500 series processor has a three-level cache hierarchy that consists of an on-core 64-KB L1 cache, a separate 256-KB L2 cache for each core, and a new inclusive, shared L3 cache of up to 8 MB. The L3 cache duplicates the data stored in the L1 and L2 caches of each core. This data duplication eliminates unnecessary searches, or snoops, to those caches and minimizes latency. Additional data tracking technology in the L3 cache ensures inter-core cache coherency. If one processor needs to access the cache or DDR-3 memory of the other processor, it uses the high-speed QPI between the two processors. Intel Hyper-Threading Technology Hyper-Threading (HT) Technology enables each core to execute two computational threads at the same time, thus, allowing each quad-core processor to simultaneously execute up to eight threads. As a result, HT Technology improves performance per watt by allowing ProLiant G6 servers to do more using the same or less power than the previous generation of ProLiant servers. Intel Turbo Boost Technology Turbo Boost gives an administrator the option to manually or automatically turn off individual cores and run the remaining cores faster than their nominal frequency, if there is power and thermal headroom to do so. The administrator can determine the headroom using criteria such as the desired number of active cores, estimated power use, and maximum processor temperature. Dynamic Power Management Dynamic Power Management works hand-in-hand with Turbo Boost to automatically optimize the performance and power use of the processor, chipset, and memory based on business requirements. In essence, Dynamic Power Management allows Intel Xeon 5500 series processors to provide greater performance using the same amount of power as previous generation Intel processors. Or, it allows them to achieve performance equivalent to previous generation processors using less power. DDR-3 memory technology ProLiant G6 servers based on the Intel Xeon 5500 series processor support DDR-3 memory technology-DDR3-800, DDR3-1066, or DDR3-1333. DDR-3 dual in-line memory modules (DIMMs) provide the same reliability, availability, and serviceability as DDR-2 DIMMs; however, DDR3 DIMMs use less power, have lower latency, and deliver higher bandwidth. DDR-3 DIMMs operate at 1.5V, compared to 1.8V for DDR-2 DIMMs. This translates into more than 25% in power savings comparing the fastest DDR-2 DIMM (DDR2-800) to the slowest DDR-3 DIMM (DDR3-800). The power savings increase to almost 35% comparing the most commonly used DIMMs, DDR2-667 and DDR3-1066. It's important to note that there are two types of DDR-3 DIMMs-registered (RDIMMs) and unbuffered (UDIMMs)-and they cannot be used together in a system. ProLiant G6 servers support up to three RDIMMs per channel or up to two UDIMMs per channel. RDIMMs have larger capacity (up to 8 GB each) than UDIMMs (up to 2 GB each). Higher-end ProLiant G6 servers support up to 18 sockets. In these servers, RDIMMs enable total memory capacity of up to 144 GB, compared to 24 GB for UDIMMs. This makes RDIMMs the ideal choice for virtualization, while UDIMMs provide cost and power savings for less memory-intensive applications. The memory channels can operate at up to 1333 MHz, but the actual speed depends on the number and type of DIMMs populating the slots. For example, in a fully-populated system using DDR3-1333 4