Consulte este artigo: A memória utilizável pode ser menor que a memória instalada em computadores baseados no Windows 7 :
A 64-bit version of Windows 7 may
report that there is only 7.1 GB of
usable system memory on a computer
that has 8 GB of memory installed.
Note: The amount of usable memory in
the examples are not exact amounts.
This is expected behavior on computers
that are running Windows 7. The
reduction in available system memory
depends on the configuration of the
following:
- The devices that are installed in the computer and the memory that is
reserved by those devices
- The ability of the motherboard to handle memory
- The System BIOS version and settings
- The version of Windows 7 that is installed (For example, Windows 7
Starter Edition only supports 2 GB of
installed memory.)
- Other system settings
For example, if you have a video card
that has 256 MB of on-board memory,
that memory must be mapped within
the first 4 GB of address space. If
4 GB of system memory is already
installed, part of that address space
must be reserved by the graphics
memory mapping. Graphics memory
mapping overwrites a part of the
system memory. These conditions reduce
the total amount of system memory that
is available to the operating system.