GIGABYTE AMD Socket AM2 Motherboard GA-3PXSL-RH - Manual (Page 31)

BIOS Setup
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Base Memory
The POST of the BIOS will determine the amount of base (or conventional) memory
installed in the system.
Extended Memory
The BIOS determines how much extended memory is present during the POST. This is the
amount of memory located above 1 MB in the C PU’s memory address map.
Total Memory
The POST of the BIOS will determine the amount of total memory installed in the system.