Memory discrepancy

I have a Dell XPS 710 running Vista Home Premium. When I run the Dell
diagnostics and select
System Info -> Memory Info, it correctly tells me that I have four 1GB
memory modules for
a total of 4GB. However, Vista's Control Panel -> System & Maintenance ->
System tells me
I have only 3GB. What has Vista done with the other 1 GB?

Jim Mehl

Hi Jim,

Vista's done nothing. It's a limitation of 32-bit addressing. There is a
total of 4GB of address space, and a portion of this, usually .7 to 1.3GB
depending on the configuration, is reserved by the system for the hardware.
The remainder, 2.7 to 3.3GB, is assigned for memory address space. Once SP1
is installed, the system will report the full amount installed.

--
Best of Luck,

Rick Rogers, aka "Nutcase" - Microsoft MVP
http://mvp.support.microsoft.com/
Windows help - www.rickrogers.org
My thoughts http://rick-mvp.blogspot.com

"Jim Mehl" <> wrote in message
news:...
>I have a Dell XPS 710 running Vista Home Premium. When I run the Dell
>diagnostics and select
> System Info -> Memory Info, it correctly tells me that I have four 1GB
> memory modules for
> a total of 4GB. However, Vista's Control Panel -> System & Maintenance ->
> System tells me
> I have only 3GB. What has Vista done with the other 1 GB?
>
> Jim Mehl

On Sun, 30 Mar 2008 09:40:40 -0700, "Jim Mehl" <> wrote:

> I have a Dell XPS 710 running Vista Home Premium. When I run the Dell
> diagnostics and select
> System Info -> Memory Info, it correctly tells me that I have four 1GB
> memory modules for
> a total of 4GB. However, Vista's Control Panel -> System & Maintenance ->
> System tells me
> I have only 3GB. What has Vista done with the other 1 GB?



Nothing. All 32-bit versions of Windows (not just Vista) 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 not
available to the operating system and applications. The amount you can
use varies, depending on what hardware you have installed, but is
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.

Also note that with SP1 installed, this has been changed so that Vista
will report the full 4GB. However, this is very misleading, since the
amount available for its use hasn't changed and will still be around
3.1GB.

--
Ken Blake, Microsoft MVP - Windows Desktop Experience
Please Reply to the Newsgroup

"Ken Blake, MVP" <> wrote in message
news:...
> Nothing. All 32-bit versions of Windows (not just Vista) have a 4GB
> address space. That's the theoretical upper limit beyond which you can
> not go.

Well, all *current*32 bit *client* versions of Windows. 32 bit Windows
Server versions can use the PAE hack to get 36 bit addressing, and use 64 GB
of RAM. But all the other 32 bit limitations of the OS remain.

Also XP prior to SP2 could do this, and Windows 2000 still can AFAIK.