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  #1 (permalink)  
Old 04-23-2008, 06:14 PM
Michel
 
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Default Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Hi,

I have 2 Dell laptops with same hardawre configuration, 4 GB RAM and Windows
XP Pro SP2.
They have been bought in an interval of one month so BIOS is not exactly at
the same version.
On the oldest one, Windows correctly displays 4GB, for instance in task
manager when the most recent one only displays 3GB.
I precise hat winmsd displays that my RAM is 4 GB in both laptops.

Sorry if it is a FAQ but I didn't find the answer when I searched in this
forum.
Thank you for reading this message and thanks to those that can help to
solve this problem.

Michel

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  #2 (permalink)  
Old 04-23-2008, 06:14 PM
smlunatick
 
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Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

On Apr 21, 7:14*am, Michel <Mic...@discussions.microsoft.com> wrote:
> Hi,
>
> I have 2 Dell laptops with same hardawre configuration, 4 GB RAM and Windows
> XP Pro SP2.
> They have been bought in an interval of one month so BIOS is not exactly at
> the same version.
> On the oldest one, Windows correctly displays 4GB, for instance in task
> manager when the most recent one only displays 3GB.
> I precise hat winmsd displays that my RAM is 4 GB in both laptops.
>
> Sorry if it is a FAQ but I didn't find the answer when I searched in this
> forum.
> Thank you for reading this message and thanks to those that can help to
> solve this problem.
>
> Michel


Laptop's usually "share" the installed RAM with the on-board video
card. Check the hardware setting so as to see the video RAM size on
each.

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  #3 (permalink)  
Old 04-23-2008, 06:14 PM
Michel
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Thanks for the answer.
It is exactly the same thing on both laptops (512 MB).
Now after installing the latest updates, the first laptop displays 3584 MB
and the second one 3072 MB.

So the first one 3584+512=4096 should give the correct value but the second
one is off by 512MB. Does it count twice the video memory?
How can I see if video RAM is taken from the installed RAM?

Regards
Michel

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  #4 (permalink)  
Old 04-23-2008, 06:14 PM
M.I.5¾
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB


"Michel" <Michel@discussions.microsoft.com> wrote in message
news:4FB9EBFB-D58C-4C9D-845A-6212EA2A6E42@microsoft.com...
> Hi,
>
> I have 2 Dell laptops with same hardawre configuration, 4 GB RAM and
> Windows
> XP Pro SP2.
> They have been bought in an interval of one month so BIOS is not exactly
> at
> the same version.
> On the oldest one, Windows correctly displays 4GB, for instance in task
> manager when the most recent one only displays 3GB.
> I precise hat winmsd displays that my RAM is 4 GB in both laptops.
>
> Sorry if it is a FAQ but I didn't find the answer when I searched in this
> forum.
> Thank you for reading this message and thanks to those that can help to
> solve this problem.
>


This is probably the most frequently asked question, and I'm surprised you
didn't find the answer, because I think it has been asked about 3 times very
recently.

Windows 32 bit operating systems are limited to a total memory addressing
space of 4 Gb.

In the case of your laptop this most likely comprises:

1. System memory
2. Video memory
3. Input/Output devices

It is this last item that causes the problems because it requires memory
address space to access these devices, which then becomes unavailable to
Windows to address real memory. The practical upshot is that the operating
system can end uop addressing (typically) 3.1 to 3.5 Gb of memory. Your
laptop may well take the video memory out of that as well (depending on the
video system - some do have dedicated memory).

The system information screen usually shows the fitted memory, but utilities
like task manager usually show the actual available memory. The fact that
your two laptops have been bought a month apart may well mean that the
hardware differs in more respects than the BIOS (these things change
unbelievably quickly). Also, the way the plug and play routines actually
allocate the addressing can often change between configurations (and is
rarely contiguous) These may account for differences in the reported memory
or the way in which it is reported.

Unless you are doing something particularly resource hungry (like editing HD
video - though you can't do this with shared video memory), you are unlikely
to notice the difference in available RAM, 3Gb being overkill for most
applications.

I wouldn't loose any sleep over it.


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  #5 (permalink)  
Old 04-23-2008, 06:15 PM
Michel
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Thank you for your post.
I indeed didn't find the answer and I posted this in several forums and you
are the first one to give me a complete answer.

The only difference I see is in BIOS, one is version A05 (01/30/2008) and
the other version A08 (02/28/2008). (Well, hard disks are also different but
I don't think it matters here.)
Both have video NVIDIA Quadro FX 1600M with 512MB memory. I think this is
internal video memory and not shared one (maybe you can confirm this, I
didn't see anything explaining this on NVidia site).
The memory reported by task manager, systeminfo and AIDA32 tool (I don't
know if you know it) are 3584 MB and 3072 MB. BIOS, winmsd and AIDA32 report
4096 MB or 2 banks of 2048 MB, so hardware is correct.

These laptops are for testing Oracle databases of different versions, so I
need all the possible memory. I currently use 2GB machines but this is too
few and I have to stop some databases when I make tests on other ones, and I
can't make some distributed processing tests.

But sure I will not loose sleep over this.

Regards
Michel

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  #6 (permalink)  
Old 04-23-2008, 06:15 PM
Paul
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Michel wrote:
> Thank you for your post.
> I indeed didn't find the answer and I posted this in several forums and you
> are the first one to give me a complete answer.
>
> The only difference I see is in BIOS, one is version A05 (01/30/2008) and
> the other version A08 (02/28/2008). (Well, hard disks are also different but
> I don't think it matters here.)
> Both have video NVIDIA Quadro FX 1600M with 512MB memory. I think this is
> internal video memory and not shared one (maybe you can confirm this, I
> didn't see anything explaining this on NVidia site).
> The memory reported by task manager, systeminfo and AIDA32 tool (I don't
> know if you know it) are 3584 MB and 3072 MB. BIOS, winmsd and AIDA32 report
> 4096 MB or 2 banks of 2048 MB, so hardware is correct.
>
> These laptops are for testing Oracle databases of different versions, so I
> need all the possible memory. I currently use 2GB machines but this is too
> few and I have to stop some databases when I make tests on other ones, and I
> can't make some distributed processing tests.
>
> But sure I will not loose sleep over this.
>
> Regards
> Michel
>


Say that the hardware had both a built-in graphics, as well as a separate
GPU. If the built-in graphics was enabled on one laptop, and disabled on
the other, perhaps that would account for a different allocation of
address space for system busses.

Some info here.

http://support.asus.com/faq/faq_righ...Language=en-us

And there is a picture here, of an address map on an affected system. The
allocation of additional PCI or PCI Express address space, seems to have
a granularity of 256MB chunks.

http://download.intel.com/support/mo...sb/ta71902.pdf

Paul
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  #7 (permalink)  
Old 04-23-2008, 06:15 PM
Michel
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB



"Paul" wrote:

> Say that the hardware had both a built-in graphics, as well as a separate
> GPU. If the built-in graphics was enabled on one laptop, and disabled on
> the other, perhaps that would account for a different allocation of
> address space for system busses.
>


How can I check this?
In both cases winmsd say there are 512MB on video board.

Regards
Michel

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  #8 (permalink)  
Old 04-23-2008, 06:15 PM
Paul
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Michel wrote:
>
> "Paul" wrote:
>
>> Say that the hardware had both a built-in graphics, as well as a separate
>> GPU. If the built-in graphics was enabled on one laptop, and disabled on
>> the other, perhaps that would account for a different allocation of
>> address space for system busses.
>>

>
> How can I check this?
> In both cases winmsd say there are 512MB on video board.
>
> Regards
> Michel
>


Look in the BIOS ?

Look in Device Manager ?

Use a copy of Everest (or Sandra) and see what hardware is reported ?

http://www.majorgeeks.com/download4181.html

Paul


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  #9 (permalink)  
Old 04-23-2008, 06:15 PM
Michel
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

No difference in BIOS.
Device manager says differences in addresses:
FD000000-FDFFFFFF => F5000000-F5FFFFFF
E0000000-EFFFFFFF => E0000000-EFFFFFFF
FA000000-FBFFFFFF => F2000000-F3FFFFFF

How can I change this?
I really appreciate your help, thanks.
Michel

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  #10 (permalink)  
Old 04-23-2008, 06:15 PM
Paul
 
Posts: n/a
Default Re: Windows XP Pro SP2 - 4GB RAM but Windows only shows 3 GB

Michel wrote:
> No difference in BIOS.
> Device manager says differences in addresses:
> FD000000-FDFFFFFF => F5000000-F5FFFFFF
> E0000000-EFFFFFFF => E0000000-EFFFFFFF
> FA000000-FBFFFFFF => F2000000-F3FFFFFF
>
> How can I change this?
> I really appreciate your help, thanks.
> Michel
>


I don't know if I can find a really good resource that
describes how that stuff works.

When I boot a Linux CD, the very first thing Linux does,
is mention the "E820" BIOS memory map. The BIOS has the
ability to define a memory map, and as far as I know, other
things respect the reservations made. That might include
the setting of the "top of memory" or "top of low memory"
registers in the Northbridge.

I'm not sure that OSes change everything when they start
up.

So what you need to find, is why the BIOS memory map,
is defined the way it is.

There is some mention of E820 here.

http://support.microsoft.com/kb/117373

I don't have a 4GB configuration here, so cannot really
test the limits of my system.

My best guess,
Paul
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