Memory Technologies; Unbuffered And Registered Dimms - HP ProLiant s6500 Introduction Manual

Figure 7. Front view of two ProLiant z6000 G6 chassis, each containing two HP ProLiant SL2x170z G6 server
trays

Memory technologies

SL6000 server trays use DDR3 memory. You can control all processor function options, including
memory mirroring and memory channel interleaving. You use the ROM-based setup utility (RBSU) for
G6 or G7 servers to do that.
You will find details about DDR3 memory in the HP paper titled
overview of system memory

Unbuffered and registered DIMMs

DDR3 DIMMs are available as both Unbuffered (UDIMMs) and 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 the
memory configuration and processor
• PC3-10600E (UDIMM)—1333, 1066, or 800 MT/s data rate, depending on the memory
configuration and processor
• PC3-10600R (RDIMM)—1333, 1066, or 800 MT/s data rate, depending on the memory
configuration and processor
You cannot mix UDIMM and RDIMM memory within a single server tray.
UDIMM configurations have 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. UDIMMs are typically less expensive than RDIMMs because
UDIMMs require fewer components.
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
technologies."
"Memory technology evolution: an
8