S2600GZ and S2600GL

Intel® Server Board S2600GZ/GL TPS Product Architecture Overview
3.2.4.3
Publishing System Memory
 The BIOS displays the “Total Memory” of the system during POST if Quiet Boot is disabled in BIOS
setup. This is the total size of memory discovered by the BIOS during POST, and is the sum of the
individual sizes of installed DDR3 DIMMs in the system.
 The BIOS displays the “Effective Memory” of the system in the BIOS setup. The term Effective Memory
refers to the total size of all DDR3 DIMMs that are active (not disabled) and not used as redundant
units.
 The BIOS provides the total memory of the system in the main page of the BIOS setup. This total is the
same as the amount described by the first bullet above.
 If Quiet Boot is disabled, the BIOS displays the total system memory on the diagnostic screen at the
end of POST. This total is the same as the amount described by the first bullet above.

Note: Some server operating systems do not display the total physical memory installed. What is displayed is
the amount of physical memory minus the approximate memory space used by system BIOS components.
These BIOS components include, but are not limited to:
 ACPI (may vary depending on the number of PCI devices detected in the system)
 ACPI NVS table
 Processor microcode
 Memory Mapped I/O (MMIO)
 Manageability Engine (ME)
 BIOS flash
3.2.4.4
Integrated Memory Controller Operating Modes
3.2.4.4.1
Independent Channel Mode
In non-ECC and x4 SDDC configurations, each channel is running independently (nonlock-step), that is, each
cache-line from memory is provided by a channel. To deliver the 64-byte cache-line of data, each channel is
bursting eight 8-byte chunks. Back to back data transfer in the same direction and within the same rank can be
sent back-to-back without any dead-cycle. The independent channel mode is the recommended method to
deliver most efficient power and bandwidth as long as the x8 SDDC is not required.
3.2.4.4.2
Lockstep Channel Mode
In lockstep channel mode the cache-line is split across channels. This is done to support Single Device Data
Correction (SDDC) for DRAM devices with 8-bit wide data ports. Also, the same address is used on both
channels, such that an address error on any channel is detectable by bad ECC. The iMC module always
accumulates 32-bytes before forwarding data so there is no latency benefit for disabling ECC.
Lockstep channels must be populated identically. That is, each DIMM in one channel must have a
corresponding DIMM of identical organization (number ranks, number banks, number rows, number columns).
DIMMs may be of different speed grades, but the iMC module will be configured to operate all DIMMs
according to the slowest parameters present by the Memory Reference Code (MRC).
Channel 0 and channel 1 can be in lockstep. Channel 2 and 3 can be in lockstep.
Performance in lockstep mode cannot be as high as with independent channels. The burst length for DDR3
DIMMs is eight which is shared between two channels that are in lockstep mode. Each channel of the pair
provides 32 bytes to produce the 64-byte cache-line. DRAMs on independent channels are configured to
deliver a burst length of eight. The maximum read bandwidth for a given Rank is half of peak. There is another
draw back in using lockstep mode, that is, higher power consumption since the total activation power is about
twice of the independent channel operation if comparing to same type of DIMMs.
Revision 2.4
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