124 Installing System Components• Single-rank and dual-rank RDIMMs of sizes 2-GB, 4-GB, and 8-GB(when available) are supported for a total of up to 96 GB.• Quad-rank RDIMMs are supported for a total of up to 96 GB.• 1-GB and 2-GB UDIMMs are supported for a total of up to 24 GB.General Memory Module Installation GuidelinesTo ensure optimal performance of your system, observe the following generalguidelines when configuring your system memory.NOTE: Memory configurations that fail to observe these guidelines can preventyour system from starting or producing any video output.• RDIMMs and UDIMMs cannot be mixed.• Except for memory channels that are unused, all populated memorychannels must have identical configurations.• In a dual-processor configuration, the memory configuration for eachprocessor must be identical.• Memory modules of different sizes can be mixed within a memory channel(for example, 2-GB and 4-GB), but all populated channels must haveidentical configurations.• For Optimizer Mode, memory modules are installed in the numeric orderof the sockets beginning with A1 or B1.• For Memory Mirroring or Advanced ECC Mode, the two sockets furthestfrom the processor are unused and memory modules are installedbeginning with socket A2 or B2 and proceeding in the following order: A2,A3, A5, and A6.• Advanced ECC Mode requires memory modules that use x4 or x8 DRAMdevice widths.• The memory speed of each channel depends on the memoryconfiguration:– For single or dual-rank memory modules:• One memory module per channel supports up to 1333 MHz.• Two memory modules per channel supports up to 1067 MHz.– For quad-rank memory modules:• One memory module per channel supports up to 1067 MHz.
