JO replied on 16-Dec-06 08:46 PM
My machine has 4 GB of RAM.  I need to know absolutely if Vista 32 Bit RTM
will support this?  I know for a fact that Windows XP Professional 32 bit
only supports up to 3 GB. I am certain Vista 64 will.   Please do not answer
this question unless you are certain.

Thank you

Rick Rogers replied on 16-Dec-06 08:53 PM

I'm certain that you will not be able to use all 4GB with the x86 version.
This is a limitation of 32-bit processing. There is only 4GB of addressing
space and some of this is used by the system. How much depends on the
hardware, but it is the remainder that can be used by memory addressing. So,
the max you can address is 4GB minus however much your system requires. This
figure could be 3.2GB, or only 2.9GB, or some other figure entirely.

Yes, you are correct that the x64 version will allow you to use all 4GB.
There are a tremendously larger amount of addresses available under 64-bit

Best of Luck,

Rick Rogers, aka "Nutcase" - Microsoft MVP
Windows help -
Colin Barnhorst replied on 16-Dec-06 08:56 PM
All 32bit operating systems can see a maximum of 4GB.  It is a mathematical
limit, not the OS.  Vista x86 like XP x86 will show a little over 3GB on
System Properties.  This is normal.  The "missing" ram is not really
missing.  It is used by the system and not presented to the user.  There is
a range of addresses at the upper end of 4GB that is reserved.  In a system
with less than 4GB these are logical addresses and are handled by the system
that way.  However, when the system has 4GB it must block out physical ram
to protect the reserved addresses.  In addition, the BIOS will reserve some
additional address space for use by devices detected by the BIOS.
JO replied on 16-Dec-06 09:15 PM
Colin, Rick,   I thank you both for the response.  Being a technet
subscriber, I have been agonizing (yes i read the other threads on this)
whether I should go with 64 bit or 32 bit.  Colin, if I understand you, the 4
GB of RAM will be used as needed by Vista 32 bit, but just not seen by the
OS, is that correct?

Seasons Greetings to one and all who read this!
Colin Barnhorst replied on 16-Dec-06 09:22 PM
By the OS and the BIOS.

In a 64bit system the OS uses much higher logical address spaces so the OS
will see all 4GB of physical ram.  Only when you had 128GB of physical ram
on a 64bit system would you see any physical ram reserved.
Colin Barnhorst replied on 16-Dec-06 09:23 PM
The "missing" ram is seen by the OS, just not by the user.
JO replied on 16-Dec-06 09:34 PM
Colin, the problem I am facing is that I have an ultra ATA Adaptec card.  It
is impossible to find 64 bit drivers.  It may never be supported.  I need
this card.  It works fine with Vista 32 bit.  However,  I have 4 Gb of RAM.
My wife is arguing with me to upgrade to the 32 bit version of Vista, and
remove a RAM chip, as she believes that Vista 32 will not use it in any way.
So, my question, if I upgrade to vista 32 bit,
will the OS be able to use the extra RAM?  Or will it just be a dummy chip
sitting there? I understand I won't see it except when the PC posts during
JO replied on 16-Dec-06 09:40 PM
Thank You!  It is being used, just not seen in the properties.  I believe I
will go with the 32 bit version and keep the extra RAM! ;)  I am in Henderson
Nevada, where is everyone else at?
Tom Lake replied on 16-Dec-06 09:53 PM
Why not go with the 64-bit version and actually be able to USE all 4GB?

Tom Lake
Malone, NY
JO replied on 16-Dec-06 09:55 PM
Whereas I do technical support VIA the phone for a living it is different
when it is your own hardware.  I did find an article on MS that addresses
this issue specifically: for one and all:
Colin Barnhorst replied on 16-Dec-06 10:03 PM
The ram allocation will done on the same principles as XP.

It is not a dummy chip under Vista any more than it is under XP.

It relieves the OS from having to use logical address space translation but
because it is system address space the OS must fence it off to keep user
programs from colliding with the system.  There is no difference between XP
and Vista in this regard except that Vista may fence off a little more than
XP needed.

Vista does indeed use the space.  The user can't tell much difference
between 3GB and 4GB but the OS sure can.
JO replied on 16-Dec-06 10:03 PM
Tom:  Because it is almost impossible to find some 64 bit drivers for my
As I study the problem further, I see that Windows 32 bit actually does use
up to 4 GB of RAM.  The system apparently reserves 1 GB of RAM for use, such
as onboard graphics, etc.
Colin Barnhorst replied on 16-Dec-06 10:04 PM
He cannot find a 64bit driver for a needed card.
Colin Barnhorst replied on 16-Dec-06 10:18 PM
I believe that the PAE swich only applies to 32bit editions of Server.
JO replied on 16-Dec-06 10:39 PM
From what I've learned, the XP boot.ini by default addresses 2 GB of RAM for

however, if you add a 3 GB parameter to Windows XP boot.ini, this will be
allocated as needed by the OS thus:

[boot loader]
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP
Professional" /noexecute=optin /fastdetect /3GB

I simply added the 3GB and restarted, with no noticeable difference.  The
missing 1 GB belongs to Windows XP.  I presume when I upgrade to Vista 32 bit
it will be similar.
JO replied on 16-Dec-06 10:53 PM
A word of caution:  You might have seen the occasional Windows Server
deployment in which there was a /3GB switch used in the server’s BOOT.INI
file. The /3GB switch changes the memory allocation so that Windows is only
allocated 1 GB of address space, and user mode processes are allocated 3 GB
of address space. Splitting the address space like this helps Windows to
better manage high demand applications such as Exchange Server. However,
Windows is configured to have a 2 GB address space for the operating system
for a reason. If you use the /3GB switch, you can severely impact Windows
ability to run multiple applications simultaneously. Furthermore, you should
never use the /3GB switch on Small Business Server or on a domain controller.
JO replied on 16-Dec-06 10:55 PM
More wisdom:  So what does this 4 GB limit mean for 32-bit machines running a
Windows operating system? Windows is designed to address a full 4 GB memory
space. Windows splits the 4 GB of available memory address space into two
separate 2 GB address spaces. One of the 2 GB address spaces is used by the
Windows operating system, and the other 2 GB address space is used for user
mode processes (applications).
Mike C. replied on 17-Dec-06 12:40 AM
It's not just Windows, it's all systems. This is not OS specific, this is a
result of the BIOS. The system cna only "address" up to 32-bits of ram. When
hardware communicates, you're really just sending data to it just like you
would store data in memory. This is why hardware in your system uses a

There is no way around it in 32-bit processing, no special switches, no file
replacements, no nothing. The maximum addressable space is 4GB--period. Your
SYSTEM (not OS) has to use a certain amount of that to be able to
communicate with devices.

A 64-bit OS does not run into this limitation.
Windows 7 - How much Memory can Vista 32 bit support?
Asked By Tim Draper on 17-Dec-06 06:59 AM
1st hand experience m8...... i have 4x 1gb sticks in my rig. ran 32bit
vista, and it was the same ram limitaion than XP 32bit does - around
2.8gb seeable/useable.

for me to see ALL 4gb (4096mb to be precise) i've had to goto vista 64bit.
not quite as simple as that tho..... different versions of vista have
max limitations

see for more info. gives both
32bit and 64bit limitations.

so just ya know, 100% definate on above info. 1st hand experience.
user on ubuntu replied on 17-Dec-08 07:40 PM
it sees it, but it does not utilize all of it.

this change was done with sp1

before that, it could not see it and it could not utilize it either..
user on ubuntu replied on 17-Dec-08 07:44 PM
it sees it, but it does not utilize all of it.

this change was done with sp1

before that, it could not see it and it could not utilize it either..
Paul Smith replied on 17-Dec-08 08:07 PM
Well I can't see your attachment for a start.  But I assume it shows 8GB on
the Computer Properties window.

This is to be expected as that particular window shows the installed RAM,
similar to what the motherboard would report.  If you look in the Task
Manager you'll see under Performance -> Physical Memory you'll see only
around 3 to 3.5GB are available.

If you want to use all your RAM install a 64-bit operating system.

Paul Smith,
Yeovil, UK.
Microsoft MVP Windows Desktop Experience.

*Remove nospam. to reply by e-mail*
ray replied on 17-Dec-08 09:20 PM
I would assume it sees it, but is unable to use it. To use more than 4gb
on a 32 bit system you can use Linux with the proper kernel.
Bob Campbell replied on 17-Dec-08 10:10 PM
Regardless of what is shown (and the above link shows nothing), 32 bit Vista
will only use around 3.2 GB of RAM.   It is mathematically impossible for a
32 bit OS to use more than 4 GB.   "Seeing" and "using" are 2 very different
things.  Look at Task Manager to see how much is actually being used.

To actually *use* it all, you need a 64 bit OS.
Bob Campbell replied on 17-Dec-08 10:12 PM
How many times are you going to ask this question?   Seeing 8 GB and using 8
GB are 2 very different things.   Your 32 bit Vista is NOT using 8 GB, it is
simply reporting it as being installed.

Your link still shows nothing.
Shawn B. replied on 17-Dec-08 10:16 PM
It will see memory above 4 GB but will simply say that the excess of 4 GB is
in use, if I am not mistaken.
Peter Foldes replied on 17-Dec-08 10:28 PM

What it shows is only that it is installed. What it actually has is no more than

Go to Start\Run and enter  winver. How much Physical memory does it report there on
the bottom of the screen. That is the actual RAM (memory that you have)


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Claude Hopper replied on 18-Dec-08 08:09 AM
So what is the maximum memory a 64 bit os can see and use?????? as
opposed to a Windows 64 bit system.
Sorken replied on 18-Dec-08 08:43 AM
64bit architecture can theoretically use 16 exabytes. However, the operating
system and mainboard would have to support it aswell. As far as i know none
do yet. But there is room to raise the limit as there is need.
Claude Hopper replied on 18-Dec-08 11:13 AM
From 3.2 gig with 32 bit max and 16 exabytes with 64 bit. That's quite
a jump for only 32 bits more.
ray replied on 18-Dec-08 11:29 AM
FALSE. PAE enables a 32 bit system to access up to 64gb if the OS is aware
of how to use it. Such Linux systems are indeed available and, I believe,
some of the MS server systems as well. There is still a 4gb limitation on
memory used by a single process.
Bob Campbell replied on 18-Dec-08 11:33 AM
Well, sort of.   If you are using PAE, you are no longer using 32 bits.
You now have 36 bits.   It is impossible for 32 bits to address more than 4

PAE is a hack and a kludge anyway, and will soon go away now that we have
real 64 bit systems.
Tim Slattery replied on 18-Dec-08 11:52 AM
The theoretical maximum would be 2**64, 16 exabytes. No current
hardware comes anywhere close.

As actually implemented, different versions of 64-bit Vista have
different limits:

Basic    8GB
Home Premium  16GB
Business, Enterprise, Ultimate   128GB.

see here:

Tim Slattery
MS MVP(Shell/User)
ray replied on 18-Dec-08 12:13 PM
But it DOES exist and is a way for a 32 bit OS (it sure as hell ain't a 64
bit OS) to address more than 4gb. You can quibble about whether it is a
'32 bit OS' or a '36 bit OS' if you want (though it obviously is not a 36
bit OS either, IMHO, since the 4gb per process limitaion remains.
Steve Thackery replied on 18-Dec-08 12:23 PM
Guys: Ray obviously has to have the last word.  I'd let him, if I were you!


Zaphod Beeblebrox replied on 18-Dec-08 01:00 PM
That's the way binary works - each bit doubles the size of the number,
so double 4GB (not 3.2 - 4GB is the total memory addressable in a 32-bit
addressing scheme, the 3.2 comes because some of that is taken by
hardware) 32 times and you get 17,179,869,184GB, or 16 exabytes.


No matter where you go, there you are!
Aaron replied on 18-Dec-08 01:16 PM
Running Vista Home Premium SP1 32 Bit,
Task Manager reports:
Total Physical Memory of 3065 MB
Total Kernel Memory of 265 MB.

Does one add the two values, or just refer to the Physical Memory?


I'm glad my Mom named me Aaron,
That's what everybody calls me.

I've seen things you people wouldn't believe.
Attack ships on fire off the shoulder of Orion.
I watched C-beams glitter in the dark near the Tannhauser gate.
All those moments will be lost in time...
like tears in rain...
Time to die.
Roy Batty - Blade Runner
ray replied on 18-Dec-08 01:35 PM
No, I simply do not like to see innaccuracies stand.
Ian D replied on 18-Dec-08 02:23 PM
There is a difference. With 32 bits you can address 4GB directly, with
36 bit PAE you must use page switching. The extra 4 bits enable 16 pages
of 4GB each, then you can use 32 bit addressing within any page.You can't
go directly from one address to another across a 4GB boundary without
page switching. With 64 bits, and the same 64 GB you can directly access
any address.

PAE is a kludge similar to expanded memory addressing back in the early
days of DOS.
Bob Campbell replied on 18-Dec-08 02:41 PM
That's why it is a kludge.   It gives a 32 bit OS 36 bits of address space
but keeps all of the other limitations of 32 bits.    The very definition of
a hack.
Peter Foldes replied on 18-Dec-08 03:46 PM
Hi Bob

Not quite true. Not all 32 bit systems are restricted to this. For example the 32
bit W2K3 and 8 Enterprise versions can see and handle up to 64 gig's in memory . My
32 bit W2K3 Enterprise at present is handling more than 4 x that of a 32 bit Vista
or XP .
Of course you are absolutely correct when you say the above  but you need to put in
Servers can only handle as much as Vista or XP which is 4gig's


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James Kosin replied on 18-Dec-08 03:49 PM
Kludge or not, it is the basic premise for how virtual memory works as
well; so, everyone has to get use to it.  Weather 32-bits, 36-bits or
64-bits doesn't matter.
When 64-bits gets supported up to the maximum limit, virtual memory will
need a boost to still allow virtual memory to work.

Peter Foldes replied on 18-Dec-08 03:53 PM

It is your stand that is inaccurate. You will never see your system as you describe
use more than 3.5 gigs of physical memory. Even if you hack it is not possible.

But if you say so Ray then it must be that in front of your eyes ONLY


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Bob Campbell replied on 18-Dec-08 03:55 PM
Yes, true.

But those are using the PAE hack.   When you turn on PAE (Physical Address
Extension) you now have 36 bits of address space.   So you are no longer
bound by the 32 bit limit.

Again, it is mathematically impossible for a 32 bit OS to address more than
4 GB.  PAE turns it into a sort-of-but-not-really 36 bit OS.  That's why PAE
is a kludge.
Bob Campbell replied on 18-Dec-08 03:59 PM
No, it has nothing to do with virtual memory.   PAE allows more PHYSICAL
memory to be addressed.   All of the other 32 bit limitations remain.
ray replied on 18-Dec-08 05:47 PM
EXACTLY! Just as I said, it is a 32 bit OS accessing more than 4gb.
Bob Campbell replied on 18-Dec-08 08:26 PM
But it is addressing more than 4 GB because it has 36 bits of address space,
and the hardware has 36 address lines.   Therefore it is no longer "a 32 bit
OS".   It is a 36 bit/32 bit hybrid.   A hack.   A kludge.

Once again, it is mathematically impossible for a 32 bit OS to address more
than 4 GB.   Once you turn on PAE, it is no longer a 32 bit OS.   It is a
32/36 bit hybrid.
Not Even Me replied on 19-Dec-08 01:52 AM
I have a V6 under the hood and a V10 in the bed of my truck, does that mean
I have a V16?
It's the same with RAM, you may be able to see it, but can you USE it all?
Due to the addressing allocation limit of 4GB in a 32 bit OS, only 4GB TOTAL
can be seen.
So if you have a 1GB video card, you're already down to 3GB.
Other overhead (NIC, Soundcard, modem, IDE controller, etc) all use a small
amount of memory and each of those reduce the total available for use by the
Bob Campbell replied on 19-Dec-08 07:14 AM
Yep.   This 3.2 GB limit out of 4 GB total is *exactly* the same situation
as the "640K limit" of DOS.   You had 20 bits of address space which gave
you 1 MB total.   360K was reserved for video cards and other resources, so
you were left with 640K of useable RAM.

1 MB seemed like a lot of RAM in 1981.   4 GB seemed like a lot of RAM in
1995.   16 EB seems like a lot of RAM today.   I wonder when we will be
whining about the "14.5 EB limit" and "Why can't I use all 16 EB of RAM I

You needed more than 20 bits then to use more than 640K.   You need more
than 32 bits today to use more than 3.2 GB.   Whether that is 36 bits with
PAE or a real 64 bit OS does not matter.   With 32 bits you are limited to
something less than 4 GB.
Ian D replied on 19-Dec-08 12:00 PM
PAE uses page switching.  To access, say 16GB, you would have 4
pages of 4GB each.  The 32 bit OS would allow access to only one
page at a time.  The page switching kludge isn't too bad for accessing
data, but running code that may cross a page boundary would present
a bit of a programming challenge.

It's all becoming irrelevant. I noticed in the latest Bestbuy flyer that
half the desktop systems have from 4 to 8 GB of RAM, and run 64
bit Vista, and all for $1k, or less.  In another year only low end PCs
will be 32 bit.  This may accelerate the development of true 64 bit
ray replied on 19-Dec-08 01:03 PM
True 64 bit applications have been around for years. In the mid 90's I was
running true 64 bit applications on a DEC Alpha - it is just MS who is so
far behind and trying to play catchup.
Bob Campbell replied on 19-Dec-08 04:07 PM
Yep.   I was in Sam's the other day.  Every desktop machine there has 64 bit
Vista and 4 GB minimum.   The "deluxe" machines had 6 GB.   I was stunned.

64 bit is mainstream right now.
Bob Campbell replied on 19-Dec-08 04:13 PM
Yeah, because there are so many DEC Alpha machines on desktops and in homes
today!    Those probably cost $50,000 in 1995 also.   Today they cost

MS isn't "far behind and playing catchup" with anything.   64 bit hardware
has only recently become widely (and cheaply) available.  There is no
Shawn B. replied on 19-Dec-08 11:32 PM
I just purchased two Dell Studio XP 435MT's (Core i7, 12GB RAM) for $1,499
including a 24" widescreen monitor with Vista 64-bit.  I'm thinking there
are just two main factors that will lead to wide spread adoption of 64-bit
(from the manufacturing and software side)

1) volume of 64-bit OS sold/installed
2) Microsoft's commitment to 64-bit (their plans to only support 64-bit OS
in the future, for example, as well as whether they make a native 64-bit
version of Office or other main software).  For example, Exchange server
2007+ is 64-bit only.  If they did that for BizTalk, SharePoint, SQL Server,
and possibly Office, then everyone will take 64-bit more seriously.

But it isn't just Microsoft and the *NIX crowd, it's the software vendors.
Right now there is lots of software I would love to have 64-bit only but the
software vendors don't provide the 64-bit option.
Borland/CodeGear/Embarcadero Delphi for example, does not even compile to
64-bit code yet.  Visual Studio, while can build 64-bit images, is still
very much a 32-bit application, as well as Office, and many device drivers.

With time, things will improve.  The mere fact that most new system's sold
today are 64-bit OS (on the Windows side) is a good indication that we're on
our way to greater industry support for 64-bit everything.

B. Smith replied on 19-Dec-08 11:44 PM
It is not.
And at least one of the best buy PC's with 8GB RAM is a friggen dog.
I saw it.
Ran like crap.
You must like sheit shoveled down your throat.
Crappy machines loaded down with useless RAM...low end graphics, and crapola
Merry Christmas....LOL.
I'd give dirt before I'd give one of those PC's.