Server Board Family Datasheet

System BIOS Intel® S5000 Server Board Family Datasheet
Revision 1.3
Intel order number D38960-006
36
3.3.7.1 Memory Sub-system Nomenclature
 FBDIMMs are organized into physical slots on memory channels that belong to memory
branches.
 Each branch can support a maximum of four DIMM sockets per channel.
 The memory channels are identified as Channel A, B, C, and D.
 Channels A and B belong to Branch 0. Channels C and D belong to Branch 1.
 The DIMM identifiers on the silkscreen on the board provide information about which
channel, and therefore which branch, they belong to. For example, DIMM_A1 is the first
slot on Channel A on Branch 0. DIMM_C1 is the first DIMM socket on Channel C on
Branch 1.
3.3.7.2 Memory Upgrade Rules
Upgrading the system memory requires careful positioning of the FBDIMMs, based on the
following factors:
 The current mode of operation
 The existing FBDIMM population
 The FBDIMM characteristics
 The optimization techniques used by the Intel® 5000 MCH to maximize FBD bandwidth.
In dual-channel mode, the adjacent channels of a branch work in lock-step to provide increase
in FBD bandwidth. Channel A and Channel B are lock-stepped when Branch 0 is configured to
support dual-channel mode, Channel C and Channel D are lock-stepped when Branch 1 is
configured for lock-step.
In single-channel mode, only Channel A, Branch 0 can be active. In this mode, Branch 1 is
always disabled. Accordingly, only FBDIMMs on Channel A are enabled. All other FBDIMMs are
disabled.
The following are the general rules to be observed when selecting and configuring memory to
obtain the best performance from the system.
 Rule 1: the Dual-channel or lock-stepped mode of operation is always the preferred
mode of operation, irrespective of the branch on which it is possible.
 Rule 2: Branch 0 is usually given precedence over Branch 1 in determining the mode of
operation. The only exception to this rule is when Branch 1 satisfies Rule #1 above, but
Branch 0 cannot.
 Rule 3: Both branches are autonomous and capable of being independently initialized.
However, the minimal upgrade for Branch 1 is DIMM_C1/DIMM_D1 such that Rule #1 is
satisfied.
 Rule 4: If an installed FBDIMM has faulty or incompatible SPD data, it will be ignored
during the lock-step selection process, and thus essentially disabled by the BIOS. If the
FBDIMM has no or missing SPD information, the slot on which it is placed will be treated
as empty by the BIOS.