Installing System Components 83General 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 and producing any video output.• RDIMMs and UDIMMs cannot be mixed.• Except for memory channels that are unused, all populated memorychannels must have identical configurations.• The memory configuration for each processor must be identical.• Memory modules of different sizes can be mixed in A1-A4 or B1-B4(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 channel furthest fromthe processor is unused and memory modules are installed beginning withchannel A1 or B1 and proceeding with channel A2 or B2.• Advanced ECC Mode requires memory modules that use x4 or x8 DRAMdevice widths.• The memory speed of each channel depends on thememory configuration:– 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.• Two memory modules per channel are limited to 800 MHz,regardless of memory module speed.• If quad-rank memory modules are mixed with single- or dual-rankmodules, the quad-rank modules must be installed in the socketswith the white release levers.• If memory modules with different speeds are installed, they operate at thespeed of the slowest installed memory module(s).
