Can WinXP (x86) see more than 2GB of ram, or not?

[mjs]

I am running WinXP Pro SP2 on an Asus A8N-SLI Deluxe motherboard (AMD64).

I've been thinking of upgrading my RAM to 4GB (from 2GB) but I keep hearing
conflicting stories about WinXP's ability (or lack of it) to recognize all
of it when running at 32 bits.

I'd like to get the truth straight from the horse's mouth - if I add 2 more
sticks of ram in there (4GB total), will my system be able to see all 4 GB?

Yes or no?

Let's put this debate to rest once and for all.

 

[Brett I. Holcomb]

Windows XP can see up to 4 gig. However, some of that 4 gig is used
by cards and other things in the system so you get 3.x gig where x is
some number like 2, 3, or 4 depending on what you have in your system.
I would suggest checking the manual for your motherboard as most of
them tell you what to expect. If the manual doesn't say check with
the motherboard manufacturer.

 

[JS]

Your system/Windows will not display the amount of ram correctly but it all
there. Just add the /3GB switch to your boot.ini to get the most out of the
4GB of ram. This option effectively gives 1GB for the OS and 3GB for
applications.

See: Memory Support and Windows Operating Systems
http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx

Available switch options for the Windows XP and the Windows Server 2003
Boot.ini files
http://support.microsoft.com/kb/833721

JS

 

[John John]

I am running WinXP Pro SP2 on an Asus A8N-SLI Deluxe motherboard (AMD64).

I've been thinking of upgrading my RAM to 4GB (from 2GB) but I keep hearing
conflicting stories about WinXP's ability (or lack of it) to recognize all
of it when running at 32 bits.

I'd like to get the truth straight from the horse's mouth - if I add 2 more
sticks of ram in there (4GB total), will my system be able to see all 4 GB?

Yes or no?

Let's put this debate to rest once and for all.

No. What Windows XP 32-bit will see depends on what hardware you have
in the computer, for most computers it ranges anywheres between 2.75 to
3.5GB. Here is the reason why 32-bit XP cannot fully use 4GB of RAM:

The problem that you are seeing is based on an older architecture
design for memory addressing. All the systems architecture up to this
point were based on a maximum of 4GB of total memory. Nobody really
thought, when this standard was designed, that this amount of memory
would actually be in use. The problem that has happened is that you
have PCI devices that require memory address ranges so that they can
properly execute their commands. These address ranges were mapped in
the upper sections of this maximum amount. Since nobody thought you
would be using up to 4GB these address ranges started around the last
500MB of the memory ranges. This range is called the T.O.M. or Top of
Memory range. This is the point in the bios where it places on hold the
amount of memory that is required by the various PCI devices that are
found on the motherboard. Thus when you have PCI cards or AGP cards
installed on your motherboard these devices hold on to memory for their
own use and take away from the maximum amount of memory that is
available for other tasks. This amount of memory can vary from a little
as 200MB all the way to 1GB of memory (or even more in select cases).
It just depends on the PCI devices you have and the amount of PCI
(including AGP) that you have installed all at once.

There is really no way to get around this basic design limitation. The
only way to get around these type of issues is to use certain new
designs that have brand new architectures (i.e 64-bit designs) that
allow memory to be mapped in area's above 4GB. The brand new Intel Xeon
designs and the AMD Opteron designs are built around 64-bit technology.
This is only ½ of the equation that you would need to find success.
You would also need to use an OS that is actually PAE or PAE aware so
that it is able to address memory above the 4GB level. To find out
about PAE you can search Microsofts website for PAE (Physical Address
Extensions) and it will explain this concept and what OS's actually are
capable of providing this benefit. Windows 2000 and Windows 2003 would
fit both of these criteria. Windows XP on the hand would not allow this
type of ability.

Microsoft has addressed this type of issue in the following Microsoft
Article (291988)
http://support.microsoft.com/default.aspx?scid=kb;en-us;291988

[end quote]

http://www.tyan.com/archive/support/html/memory_faq.html

To be able to use the full 4GB RAM you have to use a 64-bit operating
system or a 32-bit operating system that is PAE aware.

John

 

[mjs]

No. What Windows XP 32-bit will see depends on what hardware you have in
the computer, for most computers it ranges anywheres between 2.75 to
3.5GB.

So the ideal amount of ram to not have any of it go unused would be 3GB?

 

[John John]

The use of the /3GB switch will do nothing to alleviate the problem and
it may cause other severe problems. The switch should only be used for
specific reasons involving certain applications and the op has not
mentioned that he has any applications needing this.

http://blogs.technet.com/askperf/archive/2007/03/23/memory-management-demystifying-3gb.aspx

John

 

[jorgen]

Your system/Windows will not display the amount of ram correctly but it all
there. Just add the /3GB switch to your boot.ini to get the most out of the
4GB of ram. This option effectively gives 1GB for the OS and 3GB for
applications.

That switch only moves the virtual border between user and kernel space.
It won't affect how much physical address space is given to your ram modules

 

[mjs]

The use of the /3GB switch will do nothing to alleviate the problem and it
may cause other severe problems. The switch should only be used for
specific reasons involving certain applications and the op has not
mentioned that he has any applications needing this.

- Cakewalk Sonar 7 (Digital Audio Workstation)
- Photoshop CS3

These will represent more than 90% of the computer's use.

 

[John John]

So the ideal amount of ram to not have any of it go unused would be 3GB?

That is a rule of thumb figure that is often suggested. But a more
important question is "Why do you need all that RAM?" Are you
experiencing memory problems? What applications are you using that need
more RAM than what you have installed now? For most users 2GB of RAM is
already about 1GB more than they will ever need! Unless your computer
is paging adding more RAM will make little difference in the performance
of the computer, you should use Perfmon to monitor the pagefile usage
then decide if more RAM is needed for your programs and computing habits.

John

 

[Curt Christianson]

This article by MS-MVP Tim Slattery may be of interest:

4 GB RAM in Windows XP
http://members.cox.net/slatteryt/RAM.html

--
HTH,
Curt

Windows Support Center
www.aumha.org
Practically Nerded,...
http://dundats.mvps.org/Index.htm

|I am running WinXP Pro SP2 on an Asus A8N-SLI Deluxe motherboard (AMD64).
|
| I've been thinking of upgrading my RAM to 4GB (from 2GB) but I keep
hearing
| conflicting stories about WinXP's ability (or lack of it) to recognize all
| of it when running at 32 bits.
|
| I'd like to get the truth straight from the horse's mouth - if I add 2
more
| sticks of ram in there (4GB total), will my system be able to see all 4
GB?
|
| Yes or no?
|
| Let's put this debate to rest once and for all.
|
|

 

[Patrick Keenan]

I am running WinXP Pro SP2 on an Asus A8N-SLI Deluxe motherboard (AMD64).

I've been thinking of upgrading my RAM to 4GB (from 2GB) but I keep
hearing conflicting stories about WinXP's ability (or lack of it) to
recognize all of it when running at 32 bits.

I'd like to get the truth straight from the horse's mouth - if I add 2
more sticks of ram in there (4GB total), will my system be able to see all
4 GB?

Yes or no?

Let's put this debate to rest once and for all.

That was done long ago and is easy to find out.

The answer is yes, 32-bit XP can see more than 2 gig of RAM, if the board
supports it. It cannot see more than 4.

Because of the way memory is allocated by the OS and reserved for hardware
and device drivers, you can't, however, use much past 3 gig.

As to the benefits of adding RAM past 2 gig, if the apps you are actually
running don't need it, you won't see any benefits.

HTH
-pk

 

[Paul]

This article by MS-MVP Tim Slattery may be of interest:

4 GB RAM in Windows XP
http://members.cox.net/slatteryt/RAM.html

There is also this document. The table in the back, with
"experimental data", evaluates what happens with the 915G
chipset. The only problem with this data, is it is for a
chipset without remapping capability. If the chipset had
memory remapping, then it could have provided more memory
when a 64 bit OS was running.

http://dlsvr01.asus.com/pub/ASUS/mb/4GB_Rev1.pdf

The Athlon64 has remapping capability, so long as the
BIOS design includes the enable/disable for it. That does
not change the characteristics seen with a 32 bit OS, but
will improve what happens when a 64 bit OS is used.

For the A8N-SLI family, the worst case is when two video
cards are used. Some users have witnessed only 2.75GB
of RAM available with a 32 bit OS, when both cards are
present. More memory would be available, with a minor
hardware change - if the user switched to a PCI video
card (from the dark ages), then the number should go
well above the 3GB mark. Not a very nice tradeoff if
you are a gamer.

Allocations for some of the peripheral busses, seem to
be done in units of 256MB. So expect to lose memory with
that kind of granularity. If an add-in card needed 257MB
of memory space mapped in, then the BIOS would set the
allocation to 512MB. The BIOS prepares the settings of
the chipset, before the OS has a say in it. And I don't
think the OS changes the allocations when it runs. So
the Top Of Memory registers, would be set at the BIOSes
discretion. The cards are examined during POST, to decide
how much address space to allocate so they can be accessed.

http://support.asus.com/faq/faq_rig...4-D5C9-49C4-5E1B-CF724DB5C000&SLanguage=en-us

Paul

 

[dobey]

I wish people would stop infering that if your system can't "see" the extra
1GB memory it can still be used -
It can not.

If your system can't "see" the last GB memory, then it has not been mapped
meaning it won't/can't be used by the system.

RAM isn't like a deep well with a short measuring stick.

 

[Tim Slattery]

I am running WinXP Pro SP2 on an Asus A8N-SLI Deluxe motherboard (AMD64).

I've been thinking of upgrading my RAM to 4GB (from 2GB) but I keep hearing
conflicting stories about WinXP's ability (or lack of it) to recognize all
of it when running at 32 bits.

I'd like to get the truth straight from the horse's mouth - if I add 2 more
sticks of ram in there (4GB total), will my system be able to see all 4 GB?

It will not be able to use all 4GB of your RAM. See
http://members.cox.net/slatteryt/RAM.html

 

[Tim Slattery]

For the A8N-SLI family, the worst case is when two video
cards are used.

No surprise there. Modern video cards have LOTS and LOTS of RAM
onboard. Address space has to be dedicated to accessing all that
onboard RAM, which means less address space left over for accessing
system RAM. Two snazzy video cards, plus BIOS, plus PCIe overhead - it
adds up.

 

[mjs]

That is a rule of thumb figure that is often suggested. But a more
important question is "Why do you need all that RAM?"

I've already answered this question 10 times over, though I fail to see why
it affects the very basic question of whether or not WinXP can see more than
2GB of ram.

The answer is : Sonar 7 and Photoshop CS3 are 90% of the usage of this
computer, and both can use as much RAM as can be made available to them. The
DAW plays up to fifty 24-bit wavs at the same time while running as many
real-time audio effects as it can... and Photoshop's filter rendering would
be helped in no small way by more ram.

It's NOT for surfing the net or reading emails. :-S

This IS one of those situations where more RAM will help.

The question that has yet to be clearly answered is if there's any point in
my adding a 3rd stick (3GB), and if so, if there's any point in my adding a
4th (4GB).

As for my hardware, that has also been listed : the MB is an Asus A8N-SLI
Deluxe running WinXP (x86) and (x64) on two different partitions. The
principal OS is the (x86).

I find that my audio software (Sonar 7) has reached the limits of what it
can do. I'm at the end of a project and if I can relieve the bottleneck by
so much as 10%, it will help me a great deal.

So I ask again, with all this info in hand : IF I ADD A 3rd OR 4th GB OF
RAM, WILL THEY GO COMPLETELY UNUSED?

 

[mjs]

PS: I am only using a single 6600GT video card on the A8N-SLI Deluxe.

 

[mjs]

It will not be able to use all 4GB of your RAM. See
http://members.cox.net/slatteryt/RAM.html

But will it be able to use more than 2GB?

Seems everyone here is comparing apples with oranges. On one side, people
are saying I WILL be able to use more than 2GB of ram. On the other, they're
saying I WON'T be able to use all 4GB.

Something tells me the truth lies somewhere in-between. That BOTH sides are
right. That I will never be able to use 4GB of ram on WinXP x86, but that I
can probably see and use 3GB -- especially if I'm only running a single
128mb 6600GT video card (Asus EN6600GT, to be more precise).

The apps I use make high use of ram, where even the slightest increase in
performance will be a huge relief. So if adding 2 more sticks of ram (4GB
total) will allow me to use only 3.5GB, then I will add 2 more GB. Yes, that
half-GB is something I'm willing to pay $50 for.

If, on the other hand, my limit is more likely to be 3GB, then I will buy a
single stick and add it.

What I HAVEN'T seen in these exchanges is anyone inferring that 2GB is my
limit. It seems that at the very LEAST, I could add a 3rd stick. Right?

The question now becomes... do I add a 4th?

 

[Carl Kaufmann]

But will it be able to use more than 2GB?

Seems everyone here is comparing apples with oranges. On one side, people
are saying I WILL be able to use more than 2GB of ram. On the other, they're
saying I WON'T be able to use all 4GB.

32-bit Windows will be able to use (4 GiB - whatever is needed for
hardware addressing). An individual application gets to use up to 2
GiB. There are exceptions to this, but I'm not fully versed on the
details and hence will keep my mouth shut.

Something tells me the truth lies somewhere in-between. That BOTH sides are
right. That I will never be able to use 4GB of ram on WinXP x86, but that I
can probably see and use 3GB -- especially if I'm only running a single
128mb 6600GT video card (Asus EN6600GT, to be more precise).

The apps I use make high use of ram, where even the slightest increase in
performance will be a huge relief. So if adding 2 more sticks of ram (4GB
total) will allow me to use only 3.5GB, then I will add 2 more GB. Yes, that
half-GB is something I'm willing to pay $50 for.

If, on the other hand, my limit is more likely to be 3GB, then I will buy a
single stick and add it.

What I HAVEN'T seen in these exchanges is anyone inferring that 2GB is my
limit. It seems that at the very LEAST, I could add a 3rd stick. Right?

The question now becomes... do I add a 4th?

With memory so cheap these days I would get the 4th no matter what,
especially if you have a dual-channel board, or if you have 64-bit
hardware and can set your motherboard to remap the memory space.


Carl

 

[John John]

So I ask again, with all this info in hand : IF I ADD A 3rd OR 4th GB OF
RAM, WILL THEY GO COMPLETELY UNUSED?

What is it that you did not understand in the other replies in your
thread? Windows XP can only address (supply addresses) for 4GB of
memory. Memory does not mean RAM only, it means memory for everything
in the computer. Practically all the devices need memory addresses, if
you have 4gb of RAM in the machine and if the video card has 512MB you
need to supply addresses for 4.5GB or memory, but XP can only address
4GB, so it will supply the addresses to the video card and that will
reduce the available addresses for RAM to 3.5GB, it has to cut the
addresses somewhere and the only place it can cut without crippling
devices is by cutting available addresses for the RAM.

We don't know what the memory requirements for your devices are, but we
do know that they will receive addresses before the RAM and that means
that YOU WILL NOT BE ABLE TO USE ALL 4GB OF RAM. Based on common
knowledge and rules of thumb all we can say that you will not be able to
use the last 500 to 1250MB of RAM in the machine. If you want to know
the approximate exact amount look in the Device Manager and show
resources by connection. Get yourself a hexadecimal converter and
figure out the memory resources for the devices and subtract it from 4GB
and you will know approximately how much of your RAM will be usable.

John