How much RAM does Windows XP support?

**ImaNihilist** · 11-25-2005, 09:23 PM

I read this in my ASUS manual:

Quote:

IF you installed four 1GB memory modules, the system may detect
less than 3GB of total memory because of address space allocation
for other critical functions. This limitation applies to Windows XP
32-bit version operating system since it does not support PAE
(Physical Address Extension) mode.

If I were to install 4GB of memory into a maching runing Windows XP Professional what would happen? What about Windows XP Professional x64?

Freddy_Kruger · 11-25-2005, 10:46 PM

My mobo supports 4+ gigs of ram.

**ImaNihilist** · 11-25-2005, 10:57 PM

Quote:

Originally Posted by Freddy_Kruger

My mobo supports 4+ gigs of ram.

Ah, yes. The motherboard does. But what about Windows?

Freddy_Kruger · 11-25-2005, 11:05 PM

I don't know about this...It says 32 bit win sees only 2.7 gigs but 64 bit will see 16 gigs

lol.
definetly some issues there.
"
In terms of XP, 32bit should be able to SEE 4GB, right? Isn't the only issue with the 32bit XP that it can only allocate 2GB per process? Microsoft's website says this about memory:

"The major differentiator between 32-bit and 64-bit Windows is in memory support. Currently, 32-bit Windows is capable of supporting up to 4 GB of system memory, with up to 2 GB of dedicated memory per process. Windows XP 64-Bit Edition will currently support up to 16 GB of RAM, with the potential to support up to 16 TB of virtual memory as hardware capabilities and memory sizes grow. " (http://www.microsoft.com/technet/pro...e/xp64ovw.mspx)

Either way, the funny thing is that the problem is evident before Windows even begins to load. The bios POST counts up to 2.7GB, then pauses and skips to 4GB. When I run a software memory checker (which boots itself independent of any OS), it likewise only sees 2784 MB."

**ua549** · 11-26-2005, 08:39 AM

Windows supports and sees 4GB memory. The server versions support/see much more. The largest server configuration I've used has 96GB memory.

I believe the issue with Asus is the way they make their boards. I recently explored using an Opteron 170 processor as a test bed for a new server OS. I looked at the Asus boards extensively before determining that they don't meet the specifications for the OS product testing. The Asus web site clearly states that the 3GB limitation is because of resources in the south bridge.

**I4one** · 11-26-2005, 08:52 AM

i used to know some of the specifics - but haven't been up on it lately - and ua549 is correct about the asus boards;
see
http://www.microsoft.com/whdc/system...AE/PAEdrv.mspx
and
http://www.microsoft.com/whdc/system...AE/pae_os.mspx

**rock** · 11-26-2005, 09:07 AM

No matter how much ram a board or the 32-bit version of the OS supports, a single application cannot address more than 2GB of RAM. With the right compiler flag and a boot.ini switch set, you could presumambly increase that limit to 3GB, though there has been no definitive evidence of this actually working.

So lots of ram on servers is great when there are many users running many applications, but any individual application will never be able to use all that memory.

**ua549** · 11-26-2005, 10:20 AM

The 3GB option works in code that is designed to use it such as SQL and graphics manipulation. My own graphics workstation with a 4GB memory limit is always short on available memory.

**I4one** · 11-26-2005, 11:19 AM

won't 64bit apps not have this 2GB limitation as well ?

if so - i say to all coders... "'let's get a move on'"

**rock** · 11-26-2005, 12:20 PM

Quote:

Originally Posted by I4one

won't 64bit apps not have this 2GB limitation as well ?

if so - i say to all coders... "'let's get a move on'"

No, the 2GB limit is the "32-bit addressable space" limitation. The 64-bit limit is monstrous. I had the number once, but don't recall what it is right now for x64.

**ua549** · 11-26-2005, 12:23 PM

Only 32 bit Windows has the 4GB limit divided between Application and OS 2/2 or 3/1.
64 bit Windows can handle 4GB per process.

Here is a rundown on physical memory support.
Windows XP Home & Pro -- 4GB
Windows XP Pro x64 Editions -- 16GB
Windows Server 2003 Web & SBS -- 2GB
Windows Server 2003 Standard -- 4GB
Windows Server 2003 Enterprise -- 8GB
Windows Server 2003 Enterprise on X86 -- 64GB
Windows Server 2003 Enterprise on x64 -- 128GB
Windows Server 2003 Enterprise on Itanium -- 1024GB

In addition there are many proprietary modifications to the Enterprise editions that extend the memory capabilities for large proprietary multiprocessor systems such as those offered by Unisys.

**I4one** · 11-26-2005, 12:38 PM

rock;
i realize how awkwardly my question actually reads - but the answer then, is YES ! -- as in there's no 2/3GB per process limits for apps written for x64... (i.e. apps written in 64bit code, not merely 'supported' through backwards compatability).
thanks ua - there's another list somewhat like yours in the ms link i posted - and this is interesting;

>> Windows Server 2003 Web & SBS -- 2GB
>> Windows Server 2003 Standard -- 4GB

so i assume 2k3 SBS is cheaper in cost of OS vs 2k3 Standard ?
why only 2GB total ? it's a Small Business Server ?

**Variogon** · 12-08-2005, 10:01 PM

Quote:

Originally Posted by rock

No matter how much ram a board or the 32-bit version of the OS supports, a single application cannot address more than 2GB of RAM. With the right compiler flag and a boot.ini switch set, you could presumambly increase that limit to 3GB, though there has been no definitive evidence of this actually working.

So lots of ram on servers is great when there are many users running many applications, but any individual application will never be able to use all that memory.

It works. Last week I needed to render a huge 3ds max scene with about 75 million of polygons, hires textures, raytraced reflections and global ilumination. 3ds max used 2,7 gb of ram to render that monstruos scene.

**logicbunni** · 03-29-2009, 06:31 AM

Quote:

Originally Posted by ImaNihilist

Ah, yes. The motherboard does. But what about Windows?

Here's a list of how much RAM the various Windows versions and editions support (as of Nov 2004):

Windows NT 4.0: 4 GB
Windows 2000 Professional: 4 GB
Windows 2000 Standard Server: 4 GB
Windows 2000 Advanced Server: 8GB
Windows 2000 Datacenter Server: 32GB
Windows XP Professional: 4 GB
Windows Server 2003 Web Edition: 2 GB
Windows Server 2003 Standard Edition: 4 GB
Windows Server 2003 Enterprise Edition: 32 GB
Windows Server 2003 Datacenter Edition: 64 GB

http://support.microsoft.com/kb/555223

**ImaNihilist** · 03-29-2009, 11:58 AM

Thanks for answering a question from 2005, with an answer from 2004, in 2009.

Weird.

11-25-2005, 11:05 PM	#4
Freddy_Kruger Sleeps with the Fishes Join Date: Jan 2004 Location: Canada Posts: 7,770	I don't know about this...It says 32 bit win sees only 2.7 gigs but 64 bit will see 16 gigs lol. definetly some issues there. " In terms of XP, 32bit should be able to SEE 4GB, right? Isn't the only issue with the 32bit XP that it can only allocate 2GB per process? Microsoft's website says this about memory: "The major differentiator between 32-bit and 64-bit Windows is in memory support. Currently, 32-bit Windows is capable of supporting up to 4 GB of system memory, with up to 2 GB of dedicated memory per process. Windows XP 64-Bit Edition will currently support up to 16 GB of RAM, with the potential to support up to 16 TB of virtual memory as hardware capabilities and memory sizes grow. " (http://www.microsoft.com/technet/pro...e/xp64ovw.mspx) Either way, the funny thing is that the problem is evident before Windows even begins to load. The bios POST counts up to 2.7GB, then pauses and skips to 4GB. When I run a software memory checker (which boots itself independent of any OS), it likewise only sees 2784 MB." Last edited by Freddy_Kruger; 11-25-2005 at 11:06 PM.

11-26-2005, 08:39 AM	#5
ua549 morte prima di disonore Join Date: Nov 2000 Posts: 20,802	Windows supports and sees 4GB memory. The server versions support/see much more. The largest server configuration I've used has 96GB memory. I believe the issue with Asus is the way they make their boards. I recently explored using an Opteron 170 processor as a test bed for a new server OS. I looked at the Asus boards extensively before determining that they don't meet the specifications for the OS product testing. The Asus web site clearly states that the 3GB limitation is because of resources in the south bridge. __________________ Men never do evil so completely and cheerfully as when they do it from religious conviction. - Blaise Pascal (1623-1662), Pensées Retired since 1998 and enjoying every minute of it.

11-26-2005, 08:52 AM	#6
I4one BozoKiller Join Date: Oct 2003 Location: Zoso Posts: 7,636	i used to know some of the specifics - but haven't been up on it lately - and ua549 is correct about the asus boards; see http://www.microsoft.com/whdc/system...AE/PAEdrv.mspx and http://www.microsoft.com/whdc/system...AE/pae_os.mspx __________________ Delete the Electoral College - Support www.NationalPopularVote.com "The world according to DRM Bozos" I am a consumer, I'll buy anything I am a sheep, I am cattle, I follow the herd I am ignorant, a dumbass, and I am a bozo... I am the epitome of the 'rank and file' I am your next door neighbor I am 95% of American Consumers I will consume you If the light in your head hasn't come on yet, I suggest you go get a new bulb! Last edited by I4one; 11-26-2005 at 08:54 AM.

11-26-2005, 09:07 AM	#7
rock NullPointerException Join Date: Sep 2000 Location: York, PA Posts: 6,203	No matter how much ram a board or the 32-bit version of the OS supports, a single application cannot address more than 2GB of RAM. With the right compiler flag and a boot.ini switch set, you could presumambly increase that limit to 3GB, though there has been no definitive evidence of this actually working. So lots of ram on servers is great when there are many users running many applications, but any individual application will never be able to use all that memory. __________________ Open Source is free like a puppy is free. It's only when you look at an ant through a magnifying glass on a sunny day that you realise how often they burst into flames. Understanding Evolution

11-26-2005, 10:20 AM	#8
ua549 morte prima di disonore Join Date: Nov 2000 Posts: 20,802	The 3GB option works in code that is designed to use it such as SQL and graphics manipulation. My own graphics workstation with a 4GB memory limit is always short on available memory. __________________ Men never do evil so completely and cheerfully as when they do it from religious conviction. - Blaise Pascal (1623-1662), Pensées Retired since 1998 and enjoying every minute of it.

11-25-2005, 10:46 PM	#2
Freddy_Kruger Sleeps with the Fishes Join Date: Jan 2004 Location: Canada Posts: 7,770	My mobo supports 4+ gigs of ram.

11-26-2005, 11:19 AM	#9
I4one BozoKiller Join Date: Oct 2003 Location: Zoso Posts: 7,636	won't 64bit apps not have this 2GB limitation as well ? if so - i say to all coders... "'let's get a move on'" __________________ Delete the Electoral College - Support www.NationalPopularVote.com "The world according to DRM Bozos" I am a consumer, I'll buy anything I am a sheep, I am cattle, I follow the herd I am ignorant, a dumbass, and I am a bozo... I am the epitome of the 'rank and file' I am your next door neighbor I am 95% of American Consumers I will consume you If the light in your head hasn't come on yet, I suggest you go get a new bulb!

11-26-2005, 12:23 PM	#11
ua549 morte prima di disonore Join Date: Nov 2000 Posts: 20,802	Only 32 bit Windows has the 4GB limit divided between Application and OS 2/2 or 3/1. 64 bit Windows can handle 4GB per process. Here is a rundown on physical memory support. Windows XP Home & Pro -- 4GB Windows XP Pro x64 Editions -- 16GB Windows Server 2003 Web & SBS -- 2GB Windows Server 2003 Standard -- 4GB Windows Server 2003 Enterprise -- 8GB Windows Server 2003 Enterprise on X86 -- 64GB Windows Server 2003 Enterprise on x64 -- 128GB Windows Server 2003 Enterprise on Itanium -- 1024GB In addition there are many proprietary modifications to the Enterprise editions that extend the memory capabilities for large proprietary multiprocessor systems such as those offered by Unisys. __________________ Men never do evil so completely and cheerfully as when they do it from religious conviction. - Blaise Pascal (1623-1662), Pensées Retired since 1998 and enjoying every minute of it.

11-26-2005, 12:38 PM	#12
I4one BozoKiller Join Date: Oct 2003 Location: Zoso Posts: 7,636	rock; i realize how awkwardly my question actually reads - but the answer then, is YES ! -- as in there's no 2/3GB per process limits for apps written for x64... (i.e. apps written in 64bit code, not merely 'supported' through backwards compatability). thanks ua - there's another list somewhat like yours in the ms link i posted - and this is interesting; >> Windows Server 2003 Web & SBS -- 2GB >> Windows Server 2003 Standard -- 4GB so i assume 2k3 SBS is cheaper in cost of OS vs 2k3 Standard ? why only 2GB total ? it's a Small Business Server ? __________________ Delete the Electoral College - Support www.NationalPopularVote.com "The world according to DRM Bozos" I am a consumer, I'll buy anything I am a sheep, I am cattle, I follow the herd I am ignorant, a dumbass, and I am a bozo... I am the epitome of the 'rank and file' I am your next door neighbor I am 95% of American Consumers I will consume you If the light in your head hasn't come on yet, I suggest you go get a new bulb! Last edited by I4one; 11-26-2005 at 12:48 PM.

03-29-2009, 11:58 AM	#15
ImaNihilist Problem? Join Date: Nov 2001 Location: Manhattan Posts: 12,909	Thanks for answering a question from 2005, with an answer from 2004, in 2009. Weird.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode