Getting XP Pro to see 4GB of memory

[GMAN]

The x86 architecture includes PAE, which expands the address space well
above 4G. Both xp and vista includes a PAE kernel, but limits the
physical address space to 4G anyway

So would someone like me, who has Asus Commando MB, with a Intel core 2 duo
6600 processor, and 4GB of ram running XP pro w/SP2 want to enable the /PAE
switch and support in the bios, or is it just for people running this with
more than 4GB?

 

[jorgen]

So would someone like me, who has Asus Commando MB, with a Intel core 2 duo
6600 processor, and 4GB of ram running XP pro w/SP2 want to enable the /PAE
switch and support in the bios, or is it just for people running this with
more than 4GB?

You are probably already running PAE, which is needed to have hardware
support for DEP. But Microsoft has cut off access to the address space
above 4G anyway. You need one of their server editions for this, or
change to Linux or something

 

[Shenan Stanley]

So would someone like me, who has Asus Commando MB, with a Intel
core 2 duo 6600 processor, and 4GB of ram running XP pro w/SP2
want to enable the /PAE switch and support in the bios, or is it
just for people running this with more than 4GB?

You are probably already running PAE, which is needed to have
hardware support for DEP. But Microsoft has cut off access to the
address space above 4G anyway. You need one of their server
editions for this, or change to Linux or something

GMAN,

You can run a 64bit OS if you need to access the full potential of 4GB or
more of memory. How much of the 4GB that you currently have does your
system show? (System properties --> General Tab)

 

[GMAN]

GMAN,

You can run a 64bit OS if you need to access the full potential of 4GB or
more of memory. How much of the 4GB that you currently have does your
system show? (System properties --> General Tab)

2.93GB ram (Out of 4GB installed)


I understand after reading a bit that my 640MB Nvidia 8800GTS card is taking
at least that much address space, then the built in controllers, pci cards
,bios etc take their share.

 

[Daniel K. Smyth]

While MS seems to refuse to document RAMDRIVE.SYS, even that it exists, I
had success using it in previous versions of windows. I created a Virtual
Disk at boot and coppied an entire program into the virtual drive,
(AUTOEXEC.BAT), (Then resetting the program's internal path statements to
reflect the new path.) Increasing the applications speed drammatically. It
worked great on a 486 with 16MB of RAM and Windows 3.3.

While the linked article: http://support.microsoft.com/kb/555223 , addresses
the historical topic of this thread, I cannot find any authoritive docs on
creating virtual disks in XP.

The connection to the orig. topic, (this thread), is this, If a version of
windows is unable to access all of the installed RAM that the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys), then
redirect the Windows Pagefile to that Virtual Drive????

 

[Don Phillipson]

While the linked article: http://support.microsoft.com/kb/555223 , addresses
the historical topic of this thread, I cannot find any authoritive docs on
creating virtual disks in XP.
. . . If a version of
windows is unable to access all of the installed RAM that the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys), then
redirect the Windows Pagefile to that Virtual Drive????

The theme is exhaustively discussed in chap. 7 of
Microsoft WindowsXP Inside Out (2001) which suggests
the common objective is efficient use of RAM (i.e. all
the RAM available) supplemented where necessary by
a swap file. XP and NT handle this differently from
Win3, Win95 and Win98 (signalled by giving this file a
different name, unlike WIN386.SWP.)

The Win3 RAMdrive created a pseudodrive (using hard
drive space) for the same general purpose, and did
not feature in NT and XP because rendered obsolete
by Windows swap files/page files.

It seems theoretically possible to plan speed trials
of WinXP functions with and without RAM drives.
Many users would be interested in the results,
especially if they offered evidence that a RAMdrive
made these functions faster. Presumably MS programmers
made such trials in the 1990s.

 

[Tim Slattery]

The connection to the orig. topic, (this thread), is this, If a version of
windows is unable to access all of the installed RAM that the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys), then
redirect the Windows Pagefile to that Virtual Drive????

Because you would need to use some of your 4GB address space to access
the ramdrive, further reducing the amount of your RAM that could be
used for productive purposes.

The only solution to the 4GB barrier is 64-bit hardware and software.

 

[John John]

The connection to the orig. topic, (this thread), is this, If a version of
windows is unable to access all of the installed RAM that the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys), then
redirect the Windows Pagefile to that Virtual Drive????

Because the solutions that you propose don't work on NT operating
systems, they are solutions for MS-DOS and MS-DOS based operating
systems, autoexec.bat and config.sys are not used on NT systems.

Secondly, the solution you propose does not change the fact that
Microsoft 32-bit workstation operating systems cannot access RAM
addressed above the 4GB barrier and using a ram drive won't change that
fact.

The use of RAM Disks is not completely unknown to NT class operating
systems ( http://www.superspeed.com/ramdisk.php ) but using these
"drives" does not magically remove memory limits or increase the maximum
underlying usable RAM imposed by the operating system.

Time to move on to 64-bit workstation operating system if you want to
fully use 4GB or more of RAM, forget about DOS solutions.

By the way, the use of Ram Drives on NT is not completely undocumented,
Microsoft has long ago made some base information on this available,
they have even made a tool available for creating such drives:

FILE: Ramdisk.sys sample driver for Windows 2000
http://support.microsoft.com/kb/257405

I have never tried this Ramdisk.exe and I don't know if it works on
Windows XP but I don't see why it wouldn't. You will have to try it and
find out for yourself how well or not it works. Please note that the
use of this Ramdisk is not recommended on production machines and that
using this tool to deprive RAM to the operating system may create
complete havoc on your machine!

John

 

[dennis]

The only solution to the 4GB barrier is 64-bit hardware and software.

Since the hardware allows it (some hardware, anyways), I bet some with
the right knowledge would be able to write such a driver. A driver that
goes in and does some magic with the page table. I once saw an article
discussing the possibilities

 

[Daniel K. Smyth]

Thank you all for your input. I'll continue to study this topic, but your
advice is appreciated. Go to a 64 bit OS. My years of tech. supt. has
forced me to seek DOS and Windows optimization tricks to overcome many PC
and Windows shortcommings using multiple config.sys and autoexec.bat
configurations. The XP RAMDRIVE.SYS file, i discovered, has an upper limit
of 32MB, hardly enough for a Windows swap or page file anyway.

While MS seems to refuse to document RAMDRIVE.SYS, even that it exists, I
had success using it in previous versions of windows. I created a Virtual
Disk at boot and coppied an entire program into the virtual drive,
(AUTOEXEC.BAT), (Then resetting the program's internal path statements to
reflect the new path.) Increasing the applications speed drammatically.
It worked great on a 486 with 16MB of RAM and Windows 3.3.

While the linked article: http://support.microsoft.com/kb/555223 ,
addresses the historical topic of this thread, I cannot find any
authoritive docs on creating virtual disks in XP.

The connection to the orig. topic, (this thread), is this, If a version
of windows is unable to access all of the installed RAM that the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys),
then redirect the Windows Pagefile to that Virtual Drive????

Just upgraded my Windows XP SP2 box to 4GB of memory. My BIOS sees
4096MB.
I've added the /PAE option to boot.ini but it still says "3.62GB of RAM"
when I look at system properties. what am I missing?

Below is the whole boot.ini:

[boot loader]
timeout=5
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP
Professional" /PAE /fastdetect /NoExecute=OptIn
C:\CMDCONS\BOOTSECT.DAT="Microsoft Windows Recovery Console" /cmdcons

 

[Ken Blake, MVP]

Thank you all for your input. I'll continue to study this topic, but your
advice is appreciated. Go to a 64 bit OS. My years of tech. supt. has
forced me to seek DOS and Windows optimization tricks to overcome many PC
and Windows shortcommings using multiple config.sys and autoexec.bat
configurations. The XP RAMDRIVE.SYS file, i discovered, has an upper limit
of 32MB, hardly enough for a Windows swap or page file anyway.

Even if were big enough for the page file, it would make no sense to
use a RAM drive for the page file.

It would *hurt* performance. It's like borrowing from Peter to pay
Paul. You'd be taking memory away from Windows use, then giving it
back in the form of a page file in a RAM drive. Since you would create
extra need for paging in exactly the same amount as the size of the
RAM drive page file, you would accomplish nothing except the extra
overhead associated with the RAM drive.

 

[Daniel K. Smyth]

The orig problem this thread:
"If a version of windows is unable to access all of the installed RAM that
the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys), then
redirect the Windows Pagefile to that Virtual Drive????"

So if there were a way to use that Windows unaddressable memory was my
query. Basic premise: RAM access is at least 1000 times faster than any disk
access.

Windows begins using it's pagefile much sooner than it needs to and with
considerable RAM still available, (Depending on the specific system of
course), so it might be worth using 1-200MB of 4GB RAM for the pagefile.
Adding the basic windows RAM footprint, plus whatever RAM is used by common
utilities and one or two common Applications still might leave enough RAM
for a pagefile pointed to a "Virtual Disk" and the system would be faster
without robbing Windows of any RAM it isn't using.

Additionally, setting up Windows for general multi-tasking use could
sacrafice optimization, (Performance), for a specific use. Perhaps several
Hardware Profiles and several User Profiles, each comprising unique
optimization for a specific application or function. would be, for some
windows users, more desireable.

 

[Colin Barnhorst]

At 4GB of ram paging should not be much of an issue anyway.

The orig problem this thread:
"If a version of windows is unable to access all of the installed RAM that
the BIOS can
address, why not create a virtual disk in the excess RAM (config.sys),
then
redirect the Windows Pagefile to that Virtual Drive????"

So if there were a way to use that Windows unaddressable memory was my
query. Basic premise: RAM access is at least 1000 times faster than any
disk access.

Windows begins using it's pagefile much sooner than it needs to and with
considerable RAM still available, (Depending on the specific system of
course), so it might be worth using 1-200MB of 4GB RAM for the pagefile.
Adding the basic windows RAM footprint, plus whatever RAM is used by
common utilities and one or two common Applications still might leave
enough RAM for a pagefile pointed to a "Virtual Disk" and the system would
be faster without robbing Windows of any RAM it isn't using.

Additionally, setting up Windows for general multi-tasking use could
sacrafice optimization, (Performance), for a specific use. Perhaps
several Hardware Profiles and several User Profiles, each comprising
unique optimization for a specific application or function. would be, for
some windows users, more desireable.