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2 Technical Reference
2.1 Memory Resources
2.1.1 Addressable Memory
The board utilizes 32 GB of addressable system memory. Typically the address space
that is allocated for PCI Conventional bus add-in cards, PCI Express configuration
space, BIOS (SPI Flash device), and chipset overhead resides above the top of DRAM
(total system memory). On a system that has 32 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/SPI Flash device (96 Mb)
• Local APIC (19 MB)
• Direct Media Interface (40 MB)
• PCI Express configuration space (256 MB)
• PCH base address registers PCI Express ports (up to 256 MB)
• Memory-mapped I/O that is dynamically allocated for 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. All installed system memory can
be used when there is no overlap of system addresses.
2.2 Connectors and Headers
CAUTION
Only the following connectors and headers have overcurrent protection: back panel
and front panel USB.
The other internal connectors and headers are not overcurrent protected and should
connect only to devices inside the computer’s chassis, such as fans and internal
peripherals. Do not use these connectors or headers to power devices external to the
computer’s chassis. A fault in the load presented by the external devices could cause
damage to the computer, the power cable, and the external devices themselves.
Furthermore, improper connection of USB header single wire connectors may
eventually overload the overcurrent protection and cause damage to the board.
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