How to Suck All the Memory You Can Out of Windows XP

by Josh on August 23, 2007 · Comments

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solidworks tips With Vista spreading like hazy mist, XP may not be around much longer so I thought I’d get this little tip out to you before we’re swimming in the elegance of a new “desktop experience.”

I thought about this when Rob Rodriguez mentioned his computer upgrade and one of the tweaks he does called the “3G Switch” which allows you to use more memory for applications instead of the operating system. Having 2GB of physical RAM will only do so much. This tweak extends your capabilities when you’re consistently using a lot of memory.

Is this for real?
The first time I remember seeing this is in 2004 and at that time it was more of a myth or at least not recommended. But now it’s a verifiable fact that this will give you more memory to use and it’s very easy to do.

Before I show you how, all credit goes to Ed Eaton and Wayne Tiffany for figuring this out and putting the information out there. You can download the set of articles they wrote about this here. I would recommend reading it to get a better understanding.

How to get more memory

Go to Start, right click on My Computer and select Properties.
Select the Advanced tab
In the Startup and Recovery section select Settings
In the System Startup area select Edit
On the line after [operating systems] add this line:
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="XP Professional 3GB" /noexecute=optin /fastdetect /3GB /USERVA=2900

Some things to note:

If XP is installed on another partition you will need to change the partition number accordingly.
The /USERVA is the amount of RAM allocated to applications. If you get an XP error, try lowering this a little bit.

This has gotten me past the hump on a lot of large memory hungry applications. Vista is going to allow you to use a lot more physical RAM. If you’re switching, great. If you’re holding off, this will at least help ease the long wait.

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Comments

Jan

Hello SW collegue.
I have got a question about this memory trick. My VAR here in the Netherlands gave my basically the same line to type except an extra /SOS has to be added behind userva=2900.
Since I actually notice a speed slow down when using this 3GB switch I wonder if this is caused by /SOS. Does anyone have n idea here?
My Xeon system with XP and 4Gb memory runs better without the 3GB switch now and I wonder why.
regs

Josh

Available switch options for the Windows XP

Jan

Thanks for your info Josh. That helped.

Peter

Before you give the 5 instructions to modify the boot.ini, I would put in bold letters "Do not attempt this unless you have SP2." Some people might not read the article by Eaton and Tiffany and attempt this process with XP SP1.

Also, you make it sound like it will work for any program, but that's not true. In order for a program to make use of the /3GB switch, it has to have been compiled with the /largeaddressaware (LAA) switch. However, there is a way to modify an .exe file, giving it LAA support, which means it will recognize the /3GB switch. The ugly way is to use a command line editor from Microsoft called editbin.

A much nicer way is to use a program called LaaTiDo. It's a Windows program. You use the program to search for the .exe file to modify. Then you click "check" to see if it has LAA support. If it doesn't, click "Backup" to make a backup of the file. Then click "Enable" to Enable LAA support. You can then click "check" to confirm that the modified file has LAA support.

I can't test it because I only have 1GB on my system.

Read the author's web page which contains the link to the file:
http://www.musikbanken.se/TechLaaTiDo.aspx

Josh

Hey Peter, thanks for the clarification and the link to the .exe modifier. I almost assume that everyone is at SP2 at this point but very important to point out and check. To check if you are running SP, go to Windows Explorer, click help in the menu and select About Windows. It should show up after the version number. Also, ALWAYS make sure you backup the .exe before modifying!

Thanks Peter!