112 Installing System Components– 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 sockets with thewhite release levers.• If memory modules with different speeds are installed, they will operate atthe speed of the slowest installed memory module(s).Mode-Specific GuidelinesThree memory channels are allocated to each processor. The number ofchannels used and the allowable configurations depend on the memory modeselected.Advanced ECC (Lockstep) Mode SupportIn this configuration, the two channels closest to the processor are combinedto form one 128-bit channel. This mode supports Single Device DataCorrection (SDDC) for both x4- and x8-based memory modules. Memorymodules must be identical in size, speed, and technology incorresponding slots.Memory Mirroring SupportThe system supports memory mirroring if identical memory modules areinstalled in the two channels closest to the processor (memory should not beinstalled in the farthest channel). Mirroring must be enabled in the SystemSetup program. In a mirrored configuration, the total available systemmemory is one-half of the total installed physical memory.Optimizer (Independent Channel) ModeIn this mode, all three channels are populated with identical memorymodules. This mode permits a larger total memory capacity but does notsupport SDDC with x8-based memory modules.A minimal single-channel configuration of one 1 GB memory module perprocessor is also supported in this mode.
