D5400XS Technical Product Specification
39
2 Technical Reference
What This Chapter Contains
2.1 Memory Resources .......................................................................... 39
2.2 Connectors and Headers................................................................... 41
2.3 Jumper Block .................................................................................. 53
2.4 Mechanical Considerations ................................................................ 55
2.5 Electrical Considerations................................................................... 56
2.6 Thermal Considerations.................................................................... 57
2.7 Reliability ....................................................................................... 61
2.8 Environmental ................................................................................ 61
2.1 Memory Resources
2.1.1 Addressable Memory
The board can utilize 16 GB of addressable system memory. Typically the address
space that is allocated for PCI Conventional bus add-in cards, PCI Express
configuration space, BIOS (firmware hub), and chipset overhead resides above the top
of DRAM (total system memory). On a system that has 16 GB of system memory
installed, it is not possible to use all of the installed memory due to system address
space being allocated for other system critical functions. These functions include the
following:
• BIOS/firmware hub (16 Mbit)
• Local APIC (19 MB)
• Direct Media Interface (40 MB)
• Front side bus interrupts (17 MB)
• PCI Express configuration space (256 MB)
• MCH base address registers PCI Express ports (up to 256 MB)
• Memory-mapped I/O that is dynamically allocated for PCI Conventional and PCI
Express add-in cards (256 MB)
The board provides the capability to reclaim the physical memory overlapped by the
memory mapped I/O logical address space. The board remaps physical memory from
the top of usable DRAM boundary to the 4 GB boundary to an equivalent sized logical
address range located just above the 4 GB boundary.
Figure 9 shows a schematic of
the system memory map. All installed system memory can be used when there is no
overlap of system addresses.