Specifications

Functional Architecture Intel® Server Board S3420GPRX TPS

Revision 1.1

Intel order number E92065-001

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.

3.2.3.3 ECC Support

Only ECC

memory is supported on this platform.

3.2.4 Support for Mixed-speed Memory Modules

The BIOS supports memory modules of mixed speed by automatic selection of the lowest

common frequency of all memory modules (DDR3 DIMM). Each DDR3 DIMM advertises its

lowest supported clock speed through the TCKMIN parameter in its Serial-presence Data

(SPD). The BIOS uses this information to arrive at the common lowest frequency that satisfies

all installed DDR3 DIMMs.

This section describes the expected outcome on the installation of DDR3 DIMMs of different

frequencies in the system for a given user-selected frequency. The following rules apply:

 If all three single-rank/dual-rank RDIMM slots are populated on a channel, the BIOS

forces a global common frequency of 800 MHz.

 If two quad-rank RDIMM are populated on one channel, the BIOS forces a global

common frequency of 800 MHz.

 If one quad-rank RDIMM are populated on one channel, the BIOS forces a global

common frequency of 1066 MHz.

 If a maximum of only two DIMM slots are populated in the system among all channels

and one or more DIMMs support DDR3 frequency greater than 1333 MHz, the BIOS

forces a global common frequency of 1333 MHz.