Tip: Increase user process address space to 3GB (and other misc. tweaks)

If your gaming PC uses Windows XP (or Windows 2003) and you mainly use it for gaming (I have a “dedicated gaming PC” only for that and watching movies/listening to music), you can change one option in the boot.ini file to achieve two goals:

  • Force detection of 3 GB of RAM in XP (32bits/x86). I’ve seen a few systems who didn’t recognized correctly the 3 GB before this tweak.
  • Increase the user process address space to 3 GB. This way a single application can have as much as 3 GB for itself. This is great for videogames who eat almost all your PC resources.
    Note: The game’s exe must have been compiled with a flag to be “3GB-aware”, so not all games benefit from this.

The command to place on your boot.ini is “/3GB”.

 

Another common tweaks are disabling DEP/NoExecute (command “/noexecute=AlwaysOff”), moving your pagefile.sys file to another hard disk (instead of the one in which Windows is installed), or disabling pagefile at all if you have 3 or 4 GigaBytes of RAM (4 for Vista, 3 for XP).

If you have Vista you can also fully disable Aero and disable the “Desktop Window Manager Session Manager” and “Superfetch” Services. Also, if you don’t use them, disable the System Restore Points as they have a significant impact on HDD activity.

 

More info of Memory under Windows and of DEP.

 

Disclaimer: As I said, this is optimum for gaming only pcs. If you use your pc for working, development or other tasks it is not recommended for example to disable Superfetch.

Published 26 May 09 by Kartones
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Comments

27 May 09 by Tio Luiso

# re: Tip: Increase user process address space to 3GB (and other misc. tweaks)

Warning: While it's true that the /3GB switch gives User memory space 3 Gb, it's not guaranteed that any application can use it, as Mark Russinovich says here: blogs.technet.com/.../3155406.aspx

Quote: "To take advantage of the address space above the 2GB line, however, a process must have the ‘large address space aware’ flag set in its executable image"

Also, I know of certain apps (not of any game, though) that are incompatible with the /3GB switch. For example, my beloved Sharepoint isn't supported with /3GB. While that doesn't neccesarily say anything about any other app or game, it is possible that other apps don't work properly

Other than that, nice article

27 May 09 by Lobo666

# re: Tip: Increase user process address space to 3GB (and other misc. tweaks)

I've been using XP (x86 & x64) with the page file disabled for at least 5 years (when I first passed the 2 Gb physical RAM barrier).

It may seem extreme, but it's a HUGE improvement in performance. I've encountered 2 or 3 games that forces you to enable it in order to work, but everything else runs smoothly.

27 May 09 by Kartones

# re: Tip: Increase user process address space to 3GB (and other misc. tweaks)

@Tio Luiso

Yep, I know, that's why I mentioned the 3GB-aware flag. What I didn't knew is that there are incompatibilities, but we all know Sharepoint is... special xD

@Lobo666

I only enabled it recently because of Dawn of War II. As you say, having 3-4 GB of RAM is nonsense to have paging file for gaming, it only adds additional I/O to the hard disk...

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