Max RAM for Windows XP/Vista?

In lue of the soon to be launch of Windows Vista, one must wonder how much RAM this puppy will be able to take? Also, for those of us with older systems, how much RAM can Windows XP handle?

Well having been unable to find any sold data for the max RAM supported by Windows XP, I'm guessing that it maxes out at 4-8gb depending on which mobo you use. I would like to see where you all hit the firewall in this aspect.

As for Vista, well accorrding to Wikipedia, it'll take upto 128gb of RAM ( http://en.wikipedia.org/wiki/Windows_Vista ).

The reason for writing this is that I spent (and am sure quiet a few others like me did) $2500 on my first PC build 3 months ago and am not wanting to go through the whole process again in just a few weeks. I'm wondering if just plugging in an extra 2gb of RAM on my system will help stay off a huge upgrade?

Any and all advice/comments appreciated.

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Windows supports 3gig's of RAM, Vista requires 750MB to run the desktop so 2gig's minimum is recommended to run programs, I've heard that Vista is capable of supporting 8gig's of RAM.. 8O

Reply to mad-dog

I've got a friend running 4gb of Corsair XMS Dominator DDR-400 RAM in his Windows XP box. I thought 2gb was pushing it because I've not been able to find out where it maxes out.

If Vista truely is able to sport 128gb of RAM then we need much larger mobo's.

Reply to SPARTAN-117

Quote :

I've got a friend running 4gb of Corsair XMS Dominator DDR-400 RAM in his Windows XP box.

Yes, but the OS only uses 3GB...

Quote :

I thought 2gb was pushing it because I've not been able to find out where it maxes out.

You can install 4GB but the OS simply ignores 1GB of RAM

Quote :

If Vista truely is able to sport 128gb of RAM then we need much larger mobo's.

Where did you come up with 128GB of RAM, i said 8GB before... :?
I can envision motherboards stacked up like a parking garage 16 high to hold 128GB of RAM....lol

Message quoted 1 times

Reply to mad-dog

Quote :

Yes, but the OS only uses 3GB...
You can install 4GB but the OS simply ignores 1GB of RAM

That's not true.

Windows 2000 and 32-bit XP allocates 2GB for user-mode processes, and 2GB to kernel-mode processes. This allocation only becomes a problem when you start using close to 2GB of RAM. If you get close to that, you can put the /3GB switch in your BOOT.INI. That will change your allocation to 3GB/1GB user/kernel.

Regardless, some space in the range from 3GB to 4GB is mapped for access to your PCI/PCI-X/PCI-Express cards.

PAE on 2000 and 32-bit XP increases your addressable memory to 36 bits, or 64GB (16GB on older implementations). This is a memory window hack (like EMS in the DOS days) implemented in Xeons and Opterons. This goes into the BOOT.INI as well.

In 32-bit land, you can go with NUMA for large memory access. NUMA works in 64-bit as well, but 64-bit doesn't really have the same adressing limitations. Even 32-bit apps running on 64-bit benefit, as EACH PROCESS has access to its own 32-bit address space - that's 4GB per program. Not too shabby, in other words.

Two of my machines have over 4GB of RAM (one has 8GB, and the other 12GB)... they're both servers. My desktops have between 512MB and 2GB each. FWIW, I can run Vista (32-bit) fine on 1GB with Visual Studio, and tons of other programs running. 64-bit Vista seems to want more like 2GB in my experience. I can't comment on gaming requirements, though.

Just for giggles, new 64-bit Windows versions support a minimum of 16TB (yes, terabytes), with a 8TB/8TG user/kernel split. Each app has a 128GB address pool.

Cheers

Message quoted 1 times

Reply to okie

ok, well i was 1/2 right ....lol

Reply to mad-dog

Heh...

Well people at home using 32-bit XP shouldn't really need more than 2GB anyway. The software I write for work, however, is dependent on accessing tons of memory...

... that's the only reason I was able to bore everyone with the post above :roll:

Reply to okie

Nothing boring about that knowledge man, that's good stuff and i love to learn from people that are more knowledgeable than me....thanx 4 sharing
"my name is mad-dog and i am a addict"

Reply to mad-dog

Quote :

If Vista truely is able to sport 128gb of RAM then we need much larger mobo's.

Where did you come up with 128GB of RAM, i said 8GB before... :?
I can envision motherboards stacked up like a parking garage 16 high to hold 128GB of RAM....lol

That bit of info came from the Wikipedia link I listed. According to that article, all versions of Vista above Bussiness grade will be able to sport 128gb of RAM.

Reply to SPARTAN-117

I'm not sure who contributed the info in Wiki, but I got my info from my MSDN dev docs...

I'm inclined to believe that the 128GB listed at Wiki refers to the pool size limit (which is 128GB). The overall limit is still 17TB (8TB user/8TB kernel/1TB system cache).

Reply to okie

Windows XP Pro can use up to 4GB of RAM, but when you first install all of it you will only see 3 GB. this is caused by one or both of the following;
1. There is a BIOS setting that uses a portion of the RAM ans a temp file backup solution, which can be disabled in the BIOS.
2. Add the /PAE switch to the boot.ini file, this will access the full 4GB, but will limit 2GB to the OS and 2GB to other programs. If you add the /3GB switch after the /PAE it will allocate 1GB RAM to the OS, and 3GB to all other apps.

Message quoted 1 times

Reply to yuppie

From I've been reading at Wiki
http://en.wikipedia.org/wiki/Physi [...] on#Windows
"desktop versions of Windows (Windows XP, Windows Vista) limit physical address space to 4 GB for driver compatibility reasons" even if the PAE switch in BOOT.INI is enabled.

Do you actually have any machines running a 32-bit XP Pro or 32-bit Vista with over 4 GB which recognize all your RAM? I think perhaps your MSDN dev docs might be mistaken.

Here is the most current official MSDN dev document "Memory Limits for Windows Releases":
http://msdn.microsoft.com/en-us/li [...] nter).aspx
It's the printable version so you'll get a Print Dialog pop-up. Click on the O/S at the beginning of the doc you wish to research. Either:

Physical Memory Limits: Windows Vista
Physical Memory Limits: Windows XP

ANYONE: Do YOU have a machine with a 32-bit version of XP Pro or 32-bit version of Vista, with the PAE switch enabled, which recognizes more than 4 GB of RAM?

okie wrote :

Quote :

Yes, but the OS only uses 3GB...
You can install 4GB but the OS simply ignores 1GB of RAM

That's not true.

Windows 2000 and 32-bit XP allocates 2GB for user-mode processes, and 2GB to kernel-mode processes. This allocation only becomes a problem when you start using close to 2GB of RAM. If you get close to that, you can put the /3GB switch in your BOOT.INI. That will change your allocation to 3GB/1GB user/kernel.

Regardless, some space in the range from 3GB to 4GB is mapped for access to your PCI/PCI-X/PCI-Express cards.

PAE on 2000 and 32-bit XP increases your addressable memory to 36 bits, or 64GB (16GB on older implementations). This is a memory window hack (like EMS in the DOS days) implemented in Xeons and Opterons. This goes into the BOOT.INI as well.

In 32-bit land, you can go with NUMA for large memory access. NUMA works in 64-bit as well, but 64-bit doesn't really have the same adressing limitations. Even 32-bit apps running on 64-bit benefit, as EACH PROCESS has access to its own 32-bit address space - that's 4GB per program. Not too shabby, in other words.

Two of my machines have over 4GB of RAM (one has 8GB, and the other 12GB)... they're both servers. My desktops have between 512MB and 2GB each. FWIW, I can run Vista (32-bit) fine on 1GB with Visual Studio, and tons of other programs running. 64-bit Vista seems to want more like 2GB in my experience. I can't comment on gaming requirements, though.

Just for giggles, new 64-bit Windows versions support a minimum of 16TB (yes, terabytes), with a 8TB/8TG user/kernel split. Each app has a 128GB address pool.

Cheers

Message edited by Cypherdude on 08-26-2008 at 06:45:52 PM

Reply to Cypherdude

mad-dog wrote :

Quote :

If Vista truely is able to sport 128gb of RAM then we need much larger mobo's.

Where did you come up with 128GB of RAM, i said 8GB before... :?
I can envision motherboards stacked up like a parking garage 16 high to hold 128GB of RAM....lol

I realize this is an old post, but just read an article at AT http://www.anandtech.com/weblog/showpost.aspx?i=481
They were describing a Nehalem server with 144GB memory

Reply to jj14

CypherDude,

XP SP0 would use PAE to recognize over 4GB of RAM.

XP SP1 removed the support due to issues caused by many drivers when this was done since driver vendors were simply not testing this configuration.

Vista Never had that support.

64-Bit Versions of XP and Vista support far more RAM than will ever be physically installable into a PC until a point in time that both are very archaic operating systems.

Windows Server 2003 EnterPrise Edition would be the closest thing to XP you can use to recognize over 4gb of RAM for a 32-bit Windows OS. And Yes, I have some of thse machines setup.

For a Home User, They really should be using a 64-bit OS if they need that much memory.

------------------------------ If its good in theory but not in practice,
its not good theory.
Reply to zenmaster

yuppie wrote :

Windows XP Pro can use up to 4GB of RAM, but when you first install all of it you will only see 3 GB. this is caused by one or both of the following;
1. There is a BIOS setting that uses a portion of the RAM ans a temp file backup solution, which can be disabled in the BIOS.
2. Add the /PAE switch to the boot.ini file, this will access the full 4GB, but will limit 2GB to the OS and 2GB to other programs. If you add the /3GB switch after the /PAE it will allocate 1GB RAM to the OS, and 3GB to all other apps.

could you tell me how to add the PAE switch. It would be great if you can give me detailed description on how to edit boot.ini
I have 6 GB of ram installed but it shows only 3 GB in windows xp 32. My only other option is to upgrade to 64bit OS. my email address is crookdexter@hotmail.com

Reply to crookdexter

Nice, a 3yr old thread. XP can only support up to 3.5GB (most of the time) you have to have 64 BIT OS for it to recognize all your RAM. But XP 64 bit I heard has driver problems.

Reply to AKM880

Look Here

http://msdn.microsoft.com/en-us/li [...] S.85).aspx

Reply to Anonymous

Focus On

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