Enabling 4GB RAM in XP SP2

[cjoyce1980]

I've installed an extra 2GB of RAM in a DELL 745 to mae 4GB, but windows only sees 3GB and its says 4GB in the BIOS.

I've turned page file off and it only still sees 3GB.

How can i make it see this extra gig?

 

[Wile E]

Short version = you can't.

It has to do with the way the 32 bit OS addresses memory spaces.

 

[HookeyStreet]

Wile E is correct, 4GB will never be 'shown' in Windows XP

 

[theonetruewill]

Windows 32bit can only ever have just under 4GB in total memory. That includes virtual memory, RAM, and Gfx memory.

 

[Wile E]

Yeah, you'll have to move to x64 Windows, to make use of it all.

 

[mikey8684]

I also have 4GB ram on XP MCE (32Bit) and VISTA Ultimate (64Bit) in a Dual boot and both say that I only have 3.25GB in the bios & system properties but in system information it says "Total Physical Memory = 4,096MB" ....

Does this mean that its like I only have 3GB installed or is coz of binary and such that it just cant be displayed in XP ... coz my Vista Ultimate says the same in the mentioned locations but its 64Bit, which I was under the impression that 64Bit could display 4GB or more.

OR AM I JUST CONFUSING THE HELL OUT OF MYSELF AND SHOULD JUST SHUT UP

But the only thing Im woried about is --- is it still performing with the full 4GB or not ...

 

[tkpenalty]

Um guys...... ever heard of PAE?

 

[ex_reven]

Um guys...... ever heard of PAE?

that still wont do a full 4 gig...more like 2.9

 

[Wile E]

I also have 4GB ram on XP MCE (32Bit) and VISTA Ultimate (64Bit) in a Dual boot and both say that I only have 3.25GB in the bios & system properties but in system information it says "Total Physical Memory = 4,096MB" ....

Does this mean that its like I only have 3GB installed or is coz of binary and such that it just cant be displayed in XP ... coz my Vista Ultimate says the same in the mentioned locations but its 64Bit, which I was under the impression that 64Bit could display 4GB or more.

OR AM I JUST CONFUSING THE HELL OUT OF MYSELF AND SHOULD JUST SHUT UP

But the only thing Im woried about is --- is it still performing with the full 4GB or not ...

Go thru your BIOS and look for a feature called Memory Hole Remap (or something similar), and enable it.

Um guys...... ever heard of PAE?

Still won't show the full 4GB. I get 3.25GB with /pae or /3GB enabled. (Note that the /3GB switch automatically enables PAE)

 

[mikey8684]

Mine must have PAE (Physical Address Extension) enable coz it says it under the hardware list in my computer properties and says I have 3.25GB....

But still does this mean my PC is only using what it is stating or is it actually using 4GB but because its 32Bit can only display 3.25GB ...

 

[Wile E]

What is PAE ...

Physical Address Extension. It makes Windows address memory slightly differently. But do what I said in my post above yours first, then we'll talk PAE and /3GB. lol

 

[ex_reven]

physical address extension
it maps more "areas" for windows to write to as memory

 

[cjoyce1980]

using /PAE i get 3.5GB now, that still better than having a whole gig wasting away

copy of my boot.ini file

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /PAE

 

[Wile E]

using /PAE i get 3.5GB now, that still better than having a whole gig wasting away

copy of my boot.ini file

[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /PAE

I suggest the /3GB switch. It limits the kernel to 1GB and allows the rest to programs. /PAE splits it down the middle. The kernel doesn't need that much ram.

 

[cjoyce1980]

I suggest the /3GB switch. It limits the kernel to 1GB and allows the rest to programs. /PAE splits it down the middle. The kernel doesn't need that much ram.

What is the difference?

 

[Wile E]

What is the difference?

with just the PAE switch, the Windows kernel reserves 1.75GB of your 3.5GB all to itself. Programs can't access anymore than 1.75GB, in that config.

If you use /3GB instead, the kernel only reserves 1GB, leaving 2.5GB for your programs to use.

 

[EviLZeD]

usually for me xp 32bit picked up 3.25gb on my recent install its detected 3.5gb also vista 64bit
has detected all the ram

 

[cjoyce1980]

with just the PAE switch, the Windows kernel reserves 1.75GB of your 3.5GB all to itself. Programs can't access anymore than 1.75GB, in that config.

If you use /3GB instead, the kernel only reserves 1GB, leaving 2.5GB for your programs to use.

so with this switch, kernel gets 512mb and system gets 3GB? right

 

[ex_reven]

so with this switch, kernel gets 512mb and system gets 3GB? right

no. The kernel will still have 1 gig.
Ordinarily, without the switch the ram usage is split 50/50.
The 3gb switch just means that it will limit the kernel to 1 gig and give the remainder to applications etc.

 

[cjoyce1980]

no. The kernel will still have 1 gig.
Ordinarily, without the switch the ram usage is split 50/50.
The 3gb switch just means that it will limit the kernel to 1 gig and give the remainder to applications etc.

let me get this right, so with page file off, 128mb video ram and 4gb of system ram i will have
1GB for kernel
2.75GB for system

or is it......

1GB for kernel
3GB for system

 

[Wile E]

let me get this right, so with page file off, 128mb video ram and 4gb of system ram i will have
1GB for kernel
2.75GB for system

or is it......

1GB for kernel
3GB for system

1GB = kernel

The rest of what Windows sees of your ram = applications.

With out it, Windows splits the ram evenly between kernel and apps.

Note that applications CANNOT access the ram set aside for the kernel.


EDIT: Trust us, just add the /3GB switch to your boot.ini It's just better. lol

 

[cjoyce1980]

cheers guys, many thanks

 

[niko084]

I wish windows xp would use ram like Windows Server os's....

Just use it to cache instead as an os...
Like see and use all 16 gigs and just cache multiple programs on boot including your os..

 

[Was_ser]

Information for thinking:
http://www.geoffchappell.com/viewer.htm?doc=notes/windows/license/memory.htm


Follow link, and you will see that 32-bit win will work with even 8GB. Don't be frauded by M$, but keep in mind about WGA, and othe validation tools after .

I know, that thread old, but i want to post that technically x86 win will able to use all RAM

 

[Zubasa]

Information for thinking:
http://www.geoffchappell.com/viewer.htm?doc=notes/windows/license/memory.htm


Follow link, and you will see that 32-bit win will work with even 8GB. Don't be frauded by M$, but keep in mind about WGA, and othe validation tools after .

I know, that thread old, but i want to post that technically x86 win will able to use all RAM

Do you even understand why the 4GB limit is even there?
Sure you can force windows to install under 8GB ram but it doesn't meant that the extra will get utlized like it is in X86-64.
Whats the point of seeing 8GB in windows if it cannot address that memeory for application use?

One thing you need to know is the OP is using Windows XP, it is not like Win Vista that is build upon a kernal similar to Win Server 2003 .