Can XP handle 3 GB ?

[CRUST]

Of RAM by default, do I need to do any tweaking to get the best out of all that memory?

[Will404]

64 or 32 bit

Both can hamndle it, but if you have a large GPU then 32 bit may not use all the RAM and GPU memory

It can handle up to 3.6 or so GB.

64 bit can handle something like 128GB

[moogle]

with a 512mb graphics card I recieve 3.25gb on 32-bit xp. If you've got lower you'll get more
If you got SLI* then you'll get about 2.8gb.

*SLI based on 2 x 512mb cards (Applies to Crossfire too)

[0iD]

You need to use the 3gb switch in XP so it addresses it I believe

Enabling the 3GB Switch

1. Right-click My Computer. Click Properties.
2. In the System Properties dialog box, click the Advanced tab.
3. On the Advanced tab, under Startup and Recovery, click Settings.
4. In the Startup and Recovery dialog box, under System startup, click Edit. The Windows boot.ini file will be opened in Notepad.
5. Save a renamed copy of your boot.ini file somewhere on your computer in case you need to revert back to your original version of the file. Note: Boot.ini files may be different from computer to computer.
6. Highlight the following line in the boot.ini file:

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional" /fastdetect


7. Copy (Ctrl-C) and paste (Ctrl-V) the line just below the original. Note: Your exact text string may be different from the text string in this document. So be sure to copy the text string from your boot.ini file, not the text string shown here.
8. Modify the copied line to include “ /3GB”, as shown in the example below. Note: Do not overwrite any existing lines.

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS="Microsoft Windows XP Professional 3GB" /3GB /fastdetect


9. Save the boot.ini file and close Notepad.
10. Click OK to close each dialog box.
11. Reboot your computer.
12. During startup, select the 3GB option. If you do not select the 3GB option, the system will default to the 2GB total memory setting.

If there are problems at startup, you may need to update some of your drivers.

Verifying that the 3GB switch is enabled

Start a Revit session, and then open the new journal text file that was created. The Journals folder can usually be found in the C:\Program Files\Autodesk Revit Building X\Journals directory. Note: Revit Building is used as an example. If you are using Revit Structure, the folder will be named "Revit Structure." If you are using Revit Systems, the folder will be named "Revit Systems." Near the beginning of the journal, check to make sure that the TotalVirtualMemorySize equals approximately 31456000.

[cotswoldcs]

You need to use the 3gb switch in XP so it addresses it I believe

Is that still necessary if running SP3?

[Agent]

You need to use the 3gb switch in XP so it addresses it I believe

Nar, don't mess with it under XP

/3GB
This switch forces x86-based systems to allocate 3 GB of virtual address space to programs and 1 GB to the kernel and to executive components. A program must be designed to take advantage of the additional memory address space. With this switch, user mode programs can access 3 GB of memory instead of the usual 2 GB that Windows allocates to user mode programs. The switch moves the starting point of kernel memory to 3 GB. Some configurations of Microsoft Exchange Server 2003 and Microsoft Windows Server 2003 may require this switch.

http://support.microsoft.com/kb/833721

Unless you know you have software that is designed to take advantage of this, its not worth doing. The /3GB just alters how Windows deals with the memory, its not needed to use the 3GB / Windows to see it

[LuckyNV]

Indeed, don't play with that unless you have specific programs or games that can take advantage of it, otherwise Windows XP 32bit can still use around 3GB (or whichever amount you have)

The only game that I know supports this is Supreme Commander Forged Alliance.

For Vista 32bit no such mod is needed, if a program or game needs more than 2GB, Vista will give it, how generous

[Agent]

For Vista 32bit no such mod is needed, if a program or game needs more than 2GB, Vista will give it, how generous

I've seen this a few times around the web, but I'm not sure if its correct?
MSDN says: http://msdn.microsoft.com/en-us/library/aa366778.aspx

So it looks like that's saying its still only 2GB unless it has IMAGE_FILE_LARGE_ADDRESS_AWARE set?

Paul? Where are thou?

[Paul Adams]

> GO NORTH
You go north.
You are in a tunnel with exits south and north. It smells like popcorn. Paul is here.
> POKE PAUL
Ow!

http://msdn.microsoft.com/en-us/library/ms791558.aspx

The /3GB parameter is supported on Windows Server 2003, Windows XP, Windows 2000, and Windows NT. On Windows Vista and later versions of Windows, use the IncreaseUserVA element in BCDEdit.

On Windows, by default, the lower 2 GB are reserved for user-mode programs and the upper 2 GB are reserved for kernel-mode programs. You can use this parameter to test the performance of your driver when it is running in a 1 GB kernel.
...
To take advantage of the 3 GB available to user-mode programs, the program must be linked with the /LARGEADDRESSAWARE option.

As far as I am aware the same rules apply - don't use 4GT RAM tuning unless you have applications that can use the extended virtual address space for user-mode, as you're taking this from the kernel.
Most applications cannot or will not use >2GB virtual memory, so the only effect you get is to hamstring Windows.

Common misconceptions are:
- /3GB (4GT RAM tuning) has something to do with physical memory [it has nothing to do with installed memory]
- The 3GB is shared between all programs [it is 3GB virtual user-mode space per process]

[acro666]

Must be something wrong with my machine 'cos I have always had 3gb memory and it seems to work just fine. I am running XP-Pro SP 2.0 at the moment?

And I do not know what a 3gb switch is, never mind how to use it?

regards

acro666

[Paul Adams]

Physical Memory
3GB of RAM should work find on pretty much all systems (barring those with onboard graphics chipsets that use system memory) even running a 32-bit OS.

Physical memory addressing is bound by the same 32-bit limitation as virtual addressing (for the workstation version of Windows PAE doesn't help).

The BIOS reserves a chunk of the upper address space for the PCI bus, and leaves the rest for the operating system, very often this is 0.75GB (0xd0000000-0xffffffff).

So if you have 1GB of RAM, you can use 1GB.
If you have 2GB, you can use 2GB.
If you have 3GB, you can use 3GB.
If you have 4GB, you can use ~3.25GB.

If an onboard graphics chipset is used and it is given system memory for its own use, this is subtracted before the OS gets its share - so if 512MB is allocated, for example, the maximum memory for the OS can go down to 2.75GB.


Virtual Memory
For each process, the 32-bit virtual address space is divided between the process itself (user-mode, lower 2GB) and the kernel (upper 2GB, shared across every process).

This is true regardless of the physical memory installed.

A Win32 application without any special compiler options will assume it has 2GB of virtual address space to play with (0x00000000-0x7fffffff).

If a Win32 application is compiled with LARGEADDRESSAWARE, then it can potentially use up to all 4GB for itself, depending on which virtual address the kernel starts.

On a 32-bit platform, /3GB indicates the user/kernel split is 3/1, hence LARGEADDRESSAWARE applications can address up to 3GB.
(On a 64-bit platform there is no such switch, so the same applications can address up to 4GB.)

By reducing the kernel virtual address space from 2GB to 1GB you effectively halve the resources for drivers and dynamic memory allocations, which can lead to "not enough storage to complete the operation" errors.

So what benefits from /3GB? Databases and things like Exchange Server.
It has nothing to do with having 3GB or more of physical memory installed.