Functional Architecture
Intel® Server Board S3420GP TPS
Revision
2.4
Intel order number E65697-010
20
0xEE - Mismatch Error
: If more than two quad-ranked DIMMs are installed on any
channel in the system, the system halts with POST Diagnostic LED code 0xEE.
3.2.3
Publishing System Memory
The BIOS displays the Total Memory of the system during POST if Quiet Boot 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 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 active DDR3 DIMMs (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 in this section.
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 in this section.
The BIOS provides the total amount of memory in the system.
3.2.3.1
Memory Reservation for Memory-mapped Functions
A region of size 40 MB 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 PCIe functions, including a standard 64 MB or 256 MB of
standard PCI Express* MMIO configuration space.
If PAE is turned on in the operating system, the operating system reclaims all these reserved
regions.
In addition to this memory reservation, the BIOS creates another reserved region for memory-
mapped PCI Express* functions, including a standard 64 MB or 256 MB of standard PCI
Express* Memory Mapped I/O (MMIO) configuration space. This is based on the selection of
Maximize Memory below 4 GB in the BIOS Setup.
If this is set to Enabled, the BIOS maximizes usage of memory below 4 GB for an operating
system without PAE capability by limiting PCI Express* Extended Configuration Space to 64
buses rather than the standard 256 buses. This is done using the MAX_BUS_NUMBER feature
offered by the Intel
®
S3420 I/O Hub and a variably-sized Memory Mapped I/O region for the PCI
Express* functions.
3.2.3.2 High-Memory
Reclaim
When 4 GB or more of physical memory is installed (physical memory is the memory installed
as DDR3 DIMMs), the reserved memory is lost. However, the Intel
®
3420 chipset provides a
feature called high-memory reclaim, which allows the BIOS and operating system to remap the
lost physical memory into system memory above 4 GB (the system memory is the memory the
processor can see).
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 if
the PAE feature in the processor is supported and enabled. Most operating systems support this
feature. For details, see the relevant operating system manuals.
