32bit to 64bit
Posted 01 January 2012 - 05:15 PM
Posted 01 January 2012 - 06:28 PM
Posted 01 January 2012 - 07:02 PM
Umm what do you mean by the rest of the ram will be used for hardware?
Posted 01 January 2012 - 09:04 PM
This behavior is due to "memory mapped IO reservations". Those reservations overlay the physical address space and mask out those physical addresses so that they cannot be used for working memory. This is independent of the OS running on the machine.
Significant chunks of address space below 4GB (the highest address accessible via 32-bit) get reserved for use by system hardware:
BIOS including ACPI and legacy video support
PCI bus including bridges etc.
PCI Express support will reserve at least 256MB, up to 768MB depending on graphics card installed memory
What this means is a typical system may see between ~256MB and 1GB of address space below 4GB reserved for hardware use that the OS cannot access. Intel chipset specs are pretty good at explaining what address ranges gets reserved by default and in some cases call out that 1.5GB is always reserved and thus inaccessible to Windows.
Posted 02 January 2012 - 08:34 AM
Note besides being able to use the full 4Gb, 64-bit Windows 7 has a few security enhancements over the 32-bit version - always a good thing.
Posted 02 January 2012 - 02:40 PM
Posted 02 January 2012 - 04:09 PM
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