Addressable Memory

The system has been validated with up to 64 GB of addressable system memory. Typically, the address space that is allocated for 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 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/SPI Flash device (32 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 M.2 add-in cards (256 MB)
• Integrated graphics shared memory (up to 1.5 GB; 64 MB by default)