IBM 8685 Hardware Maintenance Manual - Page 93

Notes: 1. The DIMM options available for your server are 256 MB, 512 MB, and 1 GB. Your server supports a minimum of 512 MB and a maximum of 12 GB of system memory. 2. The amount of usable memory will be reduced depending on the system configuration. A certain amount of memory must be reserved below the amount of installed memory for system resources. The BIOS will display the amount of installed memory. 3. Your server comes with a minimum of two 256 MB DIMMs (for a total of 512 MB memory) installed in the DIMM 2 and DIMM 8 memory connectors (D2 and D8, respectively). You must have DIMMs installed in these connectors at all times. 4. When you install additional DIMMs, be sure to install them in pairs or quads and follow the DIMM installation sequence in the illustration in this section. A pair or quad is also known as a memory bank. See Table 7 on page 84 for the DIMM connectors in each pair or quad. 5. All the DIMMs in a single pair or quad must be the same size, speed, and type. 6. Multiple pairs or quads of DIMMs do not have to contain DIMMs of the same size, speed, and type, unless the Hot Spare Memory feature is enabled. 7. The memory board contains 12 DIMM connectors and supports two-way and four-way memory interleaving. To use the four-way memory interleaving technology in your server, you must install DIMMs in all four connectors in each populated set. 8. Install only 2.5 V, 184-pin, 72-bit, 100 MHz, double-data-rate (DDR), PC1600, registered synchronous dynamic random-access memory (SDRAM) dual inline memory modules (DIMMs) with error correcting code (ECC). Only 100 MHz, 72-bit, registered, synchronous memory is supported for the 256 MB, 512 MB, and 1 GB DIMMs. These DIMMs must be compatible with the latest PC1600 SDRAM Registered DIMM specification. For a list of supported options for your server, go to http://www.ibm.com/us/compat/ on the World Wide Web. 9. Installing or removing DIMMs changes the configuration information in the server. The Configuration/Setup Utility program automatically saves the new configuration information. When you restart the server, the system displays a message indicating that the memory configuration has changed (see "Starting the Configuration/Setup Utility program" on page 11). 10. Your server supports the Hot Spare Memory feature in the event of an active memory pair or quad of DIMM failure. This feature, when enabled, disables the failed memory from the system configuration and activates a Hot Spare Memory pair or quad of DIMMs to replace the failed pair or quad of DIMMs. Before you can enable this feature, you must also install at least one additional pair or quad of DIMMs as described in this book. To ensure proper server operation and to avoid disabling the Hot Spare Memory feature, all additional pairs or quads of DIMMs must be the same size, speed, and type as the failed pair or quad of DIMMs. You can enable the Hot Spare Memory feature through the Configuration/Setup Utility program (see "Starting the Configuration/Setup Utility program" on page 11). After you enable the Hot Spare Memory feature, the Configuration/Setup Utility program assigns the Hot Spare Memory bank according to your server configuration. If your server has a two-way interleaved configuration, the Hot Spare Memory bank becomes the DIMMs in connectors D2 and D8. If your server has a four-way interleaved configuration, the Hot Spare Memory bank becomes the DIMMs in connectors D1, D2, D7, and D8. Chapter 4. Customer replaceable units 83