Very interesting question and answers: windows 7 – Available memory differs by several GiB from what is installed – Super User.
Basically the missing memory can be due to:
- Windows licensing limitations
- Mapping of device memory into virtual memory space (especially on x86 systems)
This affects both server and client versions of Windows. Client versions are more restrictive because of the vast amounts of potentially faulty drivers involved.
Some links (read the full question for details):
- Pushing the Limits of Windows: Physical Memory – Mark Russinovich’s technical blog – TechNet Blogs.
- MemInfo v1.11 – January 2, 2008.
- The usable memory may be less than the installed memory on Windows 7-based computers.
–jeroen
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