IBM x3250 - System M3 - 4251 Installation And User Manual

Also see for System x3250: Installation guide User guide Specifications Problem determination and service guide

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IBM x3250 - System M3 - 4251 Installation And User Manual Manual pdf 47 page image

v You can use compatible DIMMs from various manufacturers in the same pair.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 specifications of a DDR3 DIMM are on a label on the DIMM, in the followingformat.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 MBps8500 = 8.53 GBps (PC3-1066 SDRAMs, 8-byte primary data bus)10600 = 10.66 GBps (PC3-1333 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 DIMMNotes:1. To determine the type of a DIMM, see the label on the DIMM. Theinformation on the label is in the format xxxxx nRxxx PC3-xxxxx-xx-xx-xxx.The numeral in the sixth numerical position indicates whether the DIMM issingle-rank (n=1), dual-rank (n=2), or quad-rank (n=4).2. The amount of usable memory is reduced, depending on the systemconfiguration. A certain amount of memory must be reserved for systemresources. To view the total amount of installed memory and the amount ofconfigured memory, run the Setup utility. For additional information, seeChapter 3, “Configuring the server,” on page 57.The following sections provide additional information specific to unbuffered andregistered DIMMs that you must consider.Unbuffered DIMMs (UDIMMs)The following notes provide information that you must consider when you installUDIMMs:v The memory channels run at the fastest common frequency of the DIMMsinstalled.v Do not use both UDIMMs and RDIMMs in the same server.Chapter 2. Installing optional devices 31