Memory optimized (independent channel) modeThis mode supports SDDC only for memory modules that use x4 device width, and this mode does notimpose any specific slot population requirements.Memory sparingNOTE: To use memory sparing, this feature must be enabled in System Setup.In this mode, one rank per channel is reserved as a spare. If persistent correctable errors are detected ona rank, the data from this rank is copied to the spare rank, and the failed rank is disabled.With memory sparing enabled, the system memory available to the operating system is reduced by onerank per channel. For example, in a dual-processor configuration with sixteen 4 GB dual-rank memorymodules, the available system memory is: 3/4 (ranks/channel) × 16 (memory modules) × 4 GB = 48 GB,and not 16 (memory modules) × 4 GB = 64 GB.NOTE: Memory sparing does not offer protection against a multi-bit uncorrectable error.NOTE: Both Advanced ECC/Lockstep and Optimizer modes support memory sparing.Memory mirroringMemory mirroring offers the strongest memory module reliability mode compared to all other modes,providing improved uncorrectable multi-bit failure protection. In a mirrored configuration, the totalavailable system memory is one half of the total installed physical memory. Half of the installed memoryis used to mirror the active memory modules. In the event of an uncorrectable error, the system switchesover to the mirrored copy. This ensures SDDC and multi-bit protection.The installation guidelines for memory modules are as follows• Memory modules must be identical in size, speed, and technology.• Memory modules installed in memory module sockets with white release levers must be identical andthe same rule applies for sockets with black and green release tabs. This ensures that identicalmemory modules are installed in matched pairs—for example, A1 with A2, A3 with A4, A5 with A6, andso on.Removing memory modulesPrerequisitesWARNING: The memory modules are hot to touch for some time after the system has beenpowered down. Allow time for the memory modules to cool before handling them. Handle thememory modules by the card edges and avoid touching the components or metallic contacts onthe memory module.CAUTION: Many repairs may only be done by a certified service technician. You should onlyperform troubleshooting and simple repairs as authorized in your product documentation, or asdirected by the online or telephone service and support team. Damage due to servicing that isnot authorized by Dell is not covered by your warranty. Read and follow the safety instructionsthat came with the product.CAUTION: To ensure proper system cooling, memory-module blanks must be installed in anymemory socket that is not occupied. Remove memory-module blanks only if you intend to installmemory modules in those sockets.1. Ensure that you read the Safety instructions.50
