IBM x3400 - System - 7975 User Manual

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Installing a memory moduleThe following notes describe the types of dual inline memory modules (DIMMs) thatthe server supports and other information that you must consider when installingDIMMs:v The server supports industry-standard, 1.8 V, 240-pin, 667 MHz, PC2-5300double-data-rate 2 (DDR2), dynamic random-access memory (DRAM) with errorcorrecting code (ECC), fully buffered dual inline memory modules (DIMMs).These DIMMs must be compatible with the latest DDR2 667 MHz DRAM fullybuffered DIMM specification. For a list of supported options for the server, seehttp://www.ibm.com/servers/eserver/serverproven/compat/us/; then, select yourcountry and navigate to the list of options for the server.v The DIMM options that are available for the server are 512 MB, 1 GB, and 2GB in x4 or x8 technology, single-rank or double-rank. The server supports aminimum of 1 GB and a maximum of 32 GB (16 GB in mirrored mode) of systemmemory. The server comes with two 512 MB DIMMs installed.v The system board provides 8 functional DIMM connectors and supports two-waymemory interleaving when DIMMs are installed in pairs. However, DIMMconnectors 3, 6, 9, and 12 are not functional. Do not install DIMMs in these fourconnectors and do not remove the DIMM thermal baffles installed in theseconnectors unless you need to replace the system board.v The memory controller has four fully buffered DIMM channels that are organizedinto two branches. Each branch has two channels, and each channel controlstwo DIMMs. DIMMs that are next to each other (for example, DIMM slot 1 andDIMM slot 4) within the channels of a branch must be identical in size, type,speed, and technology. However, the DIMMs in the slots above or below eachother within the channels of a branch do not have to be identical (for example,the DIMMs in DIMM slot 1 and DIMM slot 2 do not have to be identical). Thefollowing illustration shows how the memory controller is organized into branchesand channels with two pairs of DIMMs installed.DIMM 2DIMM 3DIMM 1DIMM 5DIMM 6DIMM 4DIMM 8DIMM 9DIMM 7DIMM 11DIMM 12DIMM 10Memory ControllerBranch 0 Branch 1Channel 0 Channel 1 Channel 2 Channel 3v The server can operate in two major modes: mirroring and non-mirroring(normal). The server can also operate in a single-channel mode when one DIMMis installed.v The server supports memory mirroring (mirroring mode) and online-sparememory.– Memory mirroring replicates and stores data on DIMMs within two branchessimultaneously. You must enable memory mirroring through theConfiguration/Setup Utility program (see “Using the Configuration/Setup Utilityprogram” on page 76). To enable memory mirroring in the Configuration/SetupUtility program, select Devices and I/O Ports → Advanced Chipset Control →Memory Branch Mode. Use the arrow keys to change the Memory BranchMode setting to Mirror; then, save your changes. When you use memorymirroring, consider the following information:28 System x3400 Types 7973, 7974, 7975, and 7976: User’s Guide