Installing a memory moduleThe following notes describe the types of DIMMs that the server supports and otherinformation that you must consider when you install DIMMs.v When you install or remove DIMMs, the server configuration informationchanges. When you restart the server, the system displays a message thatindicates that the memory configuration has changed.v The server supports only industry-standard double-data-rate 3 (DDR3), 800,1066, or 1333 MHz, PC3-10600R-999, registered or unbuffered, synchronousdynamic random-access memory (SDRAM) dual inline memory modules (DIMMs)with error correcting code (ECC). See http://www.ibm.com/servers/eserver/serverproven/compat/us/ for a list of supported memory modules for the server.– The specifications of a DDR3 DIMM are on a label on the DIMM, in thefollowing format.ggg eRxff-PC3-wwwwwm-aa-bb-ccwhere:ggg is the total capacity of the DIMM (for example, 1GB, 2GB, or 4GB)e is the number of ranks1 = single-rank2 = dual-rank4 = quad-rankff is the device organization (bit width)4 = x4 organization (4 DQ lines per SDRAM)8 = x8 organization16 = x16 organizationwwwww is the DIMM bandwidth, in MBps6400 = 6.40 GBps (PC3-800 SDRAMs, 8-byte primary data bus)8500 = 8.53 GBps (PC3-1066 SDRAMs, 8-byte primary data bus)10600 = 10.66 GBps (PC3-1333 SDRAMs, 8-byte primary data bus)12800 = 12.80 GBps PC3-1600 SDRAMs, 8-byte primary data bus)m is the DIMM typeE = Unbuffered DIMM (UDIMM) with ECC (x72-bit module data bus)R = Registered DIMM (RDIMM)U = Unbuffered DIMM with no ECC (x64-bit primary data bus)aa is the CAS latency, in clocks at maximum operating frequencybb is the JEDEC SPD Revision Encoding and Additions levelcc is the reference design file for the design of the DIMMd is the revision number of the reference design of the DIMMv The following rules apply to DDR3 DIMM speed as it relates to the number ofDIMMs in a channel:– When you install 1 DIMM per channel, the memory runs at 1333 MHz– When you install 2 DIMMs per channel, the memory runs at 1066 MHz– When you install 3 DIMMs per channel, the memory runs at 800 MHz– All channels in a server run at the fastest common frequency.– Do not install registered and unbuffered DIMMs in the same server.v The maximum memory speed is determined by the combination of themicroprocessor, DIMM speed, and the number of DIMMs installed in eachchannel.Chapter 5. Removing and replacing server components 195
