HP ProLiant SL390s HP ProLiant SL6500 Scalable System technologies - Page 7

Figure 5. HP ProLiant SL170s G6 server tray Memory technologies The SL6500 system uses DDR3 memory with options for memory mirroring and memory channel interleaving. You use the G6 or G7 server ROM-based setup utility (RBSU) to control these options. Unbuffered and registered DIMMs DDR3 DIMMs can be Unbuffered (UDIMMs) or Registered (RDIMMs). Both UDIMMs and RDIMMs support error-correcting code (ECC). There are three types of DDR3 memory: • PC3-8500R (RDIMM) -1066 or 800 megatransfers per second (MT/s) data rate, depending on memory configuration and processor • PC3-10600E (UDIMM) -1333, 1066, or 800 MT/s data rate, depending on memory configuration and processor • PC3-10600R (RDIMM) -1333, 1066, or 800 MT/s data rate, depending on memory configuration and processor Do not mix UDIMM and RDIMM memory within a single server tray. The following guidelines are useful for choosing DDR3 memory configurations: • UDIMM configurations are limited to a maximum of two UDIMMs per memory channel because the memory controller must drive the address and command signals to each DRAM chip on a channel. This results in a 24 GB maximum configuration. Because they require fewer components, UDIMMs are typically less expensive than RDIMMs. • RDIMM configurations can provide larger memory capacity because the memory controller only drives the address and command signals to a single register chip. This reduces the electrical load on the memory controller and lets the system remain stable with more memory modules. If you need large memory footprints, you can install three 8 GB RDIMMs per channel for a total of 144 GB. If properly configured through the RBSU, PC3-10600R memory modules can run at 1333 MT/s with two DIMMs per channel with no performance degradation. HP branded DIMMs have been qualified 7