Ken Blake, MVP wrote:[color=blue]
> On Wed, 4 Jun 2008 21:40:57 +0100, "Doug" <Doug
> <dougti@discussions.microsoft.com> wrote:
>[color=green][color=darkred]
>>> How can I check to see if 4GB is being made available for the system to
>>> utilize?[/color]
>> It sounds like the RAM isn't being detected. What does the BIOS show?[/color]
>
>[color=green]
>> Either way, the maximum amount of RAM you will be able to access (without
>> enabling PAE) is 3.2GB.[/color]
>
>
> Two points:
>
> 1. PAE doesn't help on Windows client operating systems, just on
> servers.
>
> 2. The maximum accessible amount is not precisely 3.2GB, but varies
> from as little as 2 to 2.5 (in rare cases) to as much as 3.5GB,
> depending on your hardware configuration. Here's my standard post on
> this subject:
>
> All 32-bit versions of Windows (not just XP) have a 4GB address space.
> That's the theoretical upper limit beyond which you can not go.
>
> But you can't use the entire 4GB of address space. Even though you
> have a 4GB address space, you can only use *around* 3.1GB of RAM.
> That's because some of that space is used by hardware and is not
> available to the operating system and applications. The amount you can
> use varies, depending on what hardware you have installed, but can
> range from as little as 2GB to as much as 3.5GB. It's usually around
> 3.1GB.
>
> Note that the hardware is using the address *space*, not the actual
> RAM itself. The rest of the RAM goes unused because there is no
> address space to map it too.
>[/color]
Does the above mean as follows?

BIOS and System|Properties show correct size of installed RAM while
System Tools|System Information and Task Manager|Performance show the
maximum usable part of the installed RAM. The maximum usable part could
be as low as 2GB. Therefor,if 4GB is installed and Task
Manager|Performance indicates that the Total Physical Memory is 2GB,
then half of the installed RAM is waisted.