Technical Product Specification

Table Of Contents
Functional Architecture Intel
®
Server Board S5400SF TPS
Revision 2.02
Intel order number: D92944-007
28
system, the BIOS halts with a POST Diagnostic LED code 0xE1 (no memory detected)
and halts the system.
Any of the above errors causes a memory error beep code.
3.2.3.8.3 Publishing System Memory
The BIOS displays the “Total Memory” of the system during POST if Display Logo is
disabled in the 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 FBDIMMs 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 FBDIMMs 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 Display Logo 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.
The BIOS provides the total amount of memory in the system by supporting the EFI
Boot Service function, GetMemoryMap().
The BIOS provides the total amount of memory in the system by supporting the INT
15h, E820h function. See the Advanced Configuration and Power Interface
Specification, Revision 2.0 for details.
Note: Memory between 4 GB and 4 GB minus 512 MB is not accessible for use by the
operating system and may be lost to the user. This area is reserved for the BIOS, APIC
configuration space, and virtual video memory space. Memory is also reserved for PCI/PCI-
X/PCI Express* resources. This means that if 4 GB of memory is installed, 3.5 GB or less of this
memory is usable. The chipset allows the remapping of unused memory above the 4 GB
address. To take advantage of this, turn on the Physical Address Extensions (PAE) in your
operating system.
A region of size 0.25 GB of memory below 4 GB is always reserved for mapping chipset,
processor and BIOS (flash) spaces as memory-mapped I/O regions. This region appears as a
loss of memory to the operating system. In addition to this loss, the BIOS creates another
reserved region for memory-mapped PCI Express* functions, including a standard 0.25 GB of
standard PCI Express configuration space. This memory is reclaimed by the operating system if
PAE is turned on in the operating system.
When 4 GB or more of physical memory is installed (physical memory is the memory installed
as FBDIMMs), the reserved memory is lost. However, the Intel
®
5400 Chipset provides a feature
called High-memory reclaim, that allows the BIOS and the operating system to remap the lost
physical memory into system memory above 4 GB (the system memory is the memory that can
be seen by the processor).
The BIOS always enables high-memory reclaim if it discovers installed physical memory equal
to or greater than 4 GB. For the operating system, the reclaimed memory is recoverable only
when it supports and enables the PAE feature in the processor. Most operating systems support
this feature. For details, see the relevant operating system manuals.