User:Kelmych/Fallout3 INIs

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Fallout 3 INI Tweak Guide

Info-Logo.png Notice: This is an ancillary page for the Clear and Present DangerGuide for Fallout 3, created to reduce the length of that guide. It is based on the Skyrim INI Guide.

The steps in this part of the guide can be applied at any time. If fINIp has been used previously there is no need to uninstall anything.

INI Tweaks Initial Steps

This guide is intended to be comprehensive, and includes all INI tweaks recommended for Fallout 3. Users who want more details on the entries in the Fallout.ini and FalloutPrefs.ini files should read at least the first three sections of the Skyrim INI Guide and DoubleYou's forum thread on valid Fallout 3 INI settings. DoubleYou's post includes all the valid entries for the Fallout.ini and FalloutPrefs.ini files. Any recommendations from INI tweak guides or internet forum posts should be ignored whenever they suggest adding entries that are not in the list compiled by DoubleYou. The entries in the last post in DoubleYou's forum thread work for all versions of Fallout 3 including the DVD, Steam and GOG versions.

The following instructions modify the two Fallout INIs: Fallout.ini and FalloutPrefs.ini! These are located in the %USERPROFILE%\(My )Documents\My games\Fallout3 folder. These two files should be backed up now (recommended) or at least prior to the step below that replace these files. If there is a problem later the backup versions allow reverting to the original INI files.

Open Mod Organizer then disable Automatic Archive Validation by clicking the profile button at top, highlighting your profile(s), and unchecking the Automatic Archive Invalidation checkbox. Close MO.

The first step makes use of the Bethini program. This can be potentially used at any time, but note that it replaces the Fallout.ini and FalloutPrefs.ini files in the %USERPROFILE%\(My )Documents\My games\Fallout3 folder, and will require reentry of any INI tweaks used for Fallout 3 in all of the Mod Organizer profiles that are actively used. If the [Default] selection is used all of the mod selections in the modlist.txt file in the current profile's folder in MO will be removed, so using this UI selection should typically only be used when initially setting up Fallout 3.
The Fallout Launcher runs as part of the installation process when running this utility, so be prepared to redo the entries made previously during the last part of the steps in the Pre-Installation Checklist section of the FO3 guide.


  • Author: DoubleYou
  • Version: v2.7
  • Notes: The Fallout.ini and FalloutPrefs.ini INI configuration files installed with the Fallout game have many errors (at least in the DVD and Steam versions). This program replaces the existing INI files with versions which include only valid entries. This version includes some Fallout 3 specific changes.
  • Fallout NV Equivalent: same program
  • Installation:

Download the main file. Run the installer, following the on-screen instructions.
During installation Mod Organizer users should use the Bethini Setup tab and select the MO profile they wish to use via the INI Path setting. After Bethini runs the INI files in this profile will be changed. Carefully read the warnings. Ideally backups of the original INI files were made before running this installer.
When the new INI files have been created the Fallout Launcher will run to complete the generation of the INI files. Make any changes needed, including ensuring that the screen resolution shown in the Launcher corresponds to the resolution used for monitor being used for the game.
Exit the Fallout Launcher, which builds expanded versions of the INI files.

Warning-Logo.png      Warning:To avoid 'unapproved' alterations to these two INI configuration files, STEP recommends that users set game INI files as read only after the Launcher settings seem correct. In addition, it is recommended that backup copies of these two new INI files be created in case the original versions become corrupted.

The INI files have been changed, so INI tweaks from the Fallout INI and FalloutPrefs INI subsections of this INI subguide then need to be reapplied. When this is complete the same steps can be done for other active MO profiles, or if the INI tweaks are the same for some other profiles the edited Fallout.ini and FalloutPrefs.ini files can be copied to the other Profile folders that use the same INI tweaks
Note that in addition to re-entering the INI tweaks, Archive Invalidation needs to be re-enabled for each MO Profile.

Applying the INI Tweaks

For tweaks that affect game performance the potential performance impact is indicated. Create the following at the end of each of the indicated INI sections. Sections are marked by names within square brackets '[ ]', and some of these sections may already exist, but for those that do not, create the section. Carefully check that ...

  1. no duplicate entries are created,
  2. that all entries are placed into the correct section, and
  3. that all sections are properly defined:

Mod Organizer Guide
Using the Tools > The MO INI Editor is typically used for this section. To access it, click the MO puzzle iconPuzzle mo.png and choose INI Editor. When the editor is open, use the find function (ctrl-f) to quick find the line that needs to be edited.

Alternatively, the [Configurator] tool prevents any editing mistakes. Open the tool, click [Basic] to get the Advanced options, and choose the applicable section from the combo box. Then find the applicable setting and alter as indicated below.
For either editor, click the [Save] button after each change and close the dialog when finished. If the revised INI files are intended for use with multiple MO profiles, then copy the new versions to these other MO profiles.

Fallout INI

Info-Logo.png      Notice:#Clear and Present Danger Guide for Fallout 3 DOES NOT officially recommend all of the following settings, but rather that all of the following INI entries are valid. These settings may improve the user experience, but each setting will be system/environment dependent.

Each of the following entries can be pasted directly into the INI (if editing manually). The entry descriptions are commented, so they will not be interpreted by the game at startup. Alternatively, these descriptions can be omitted. The fonts used in the DarNified UI mod are not included in the INI tweaks since they are automatically added at runtime by the UIO - UI Organizer mod. The GOG version of Fallout 3 has some different INI default entries than the DVD/Steam version.

 bUseThreadedAI=1   ;often, but perhaps not always, needed in Fallout 3 with multi-core CPUs to avoid a CTD during launch. Not needed (already present) when using GOG version.
 iNumHWThreads=2  ;often, but perhaps not always, needed in Fallout 3 with multi-core CPUs to avoid a CTD during launch.
 bLoadFaceGenHeadEGTFiles = 1  ;Allow facial morphs from mods to work correctly
;Remove mouse acceleration. These 4 values are not needed (already present) when using GOG version.
;recommended changes from ''Flora Overhaul''
;grass size value improves the density and thus the look of the grass but reduces performance
 iMinGrassSize=40  ; increase this to 80 or 140 to reduce grass density and improve game performance if needed.
 iMaxGrassTypesPerTexure=6       ;increase grass diversity with a small cost to performance (yes, 'texure' and not 'texture'),use only with Forested Edition. Use the default otherwise.
;intended to improve the effects of lighting when it's dark, from ''Fallout Street Lights''
;installation instructions for this mod include details on how to add these ini settings as ini tweaks associated with the mod vs. adding them here
;they could reduce game performance so if they are used the game performance should be tested after installation

FalloutPrefs INI

iMaxAnisotropy=0    ;Anisotropic Filtering - set this to zero, as it should be controlled via the graphics driver.
iMultiSample=4    ;Antialiasing - keep the value set by the Fallout Launcher for now
iSize W=1920  ;replace this with your system monitor width in pixels
iSize H=1080  ;replace this with your system monitor height in pixels
 fGrassStartFadeDistance=18000    ;push back the distance for grasses to fade from 3 to 5 cells (minor performance hit)

FalloutPrefs.ini and Key Bindings

Fallout 3 stores base key bindings in FalloutPrefs.ini , as discussed in this thread; some key bindings are stored in the xml files used for the UI files. The key bindings can be modified in the game, but when Mod Organizer is used this is a bad idea. Mod Organizer does not expect changes in the INI files while the game is running. and won't save the changes using the normal mechanisms. If key key bindings are changed for Fallout 3 it is strongly recommended that this be done with the INI editor in MO before running the game.

GamerPoets INI Recommendations =

As part of the Modding Fallout 3 : My Way : Pre Mod .ini Files (by GamerPoets)
GamerPoets demonstrates Fallout 3 ini file changes
GamerPoets generated a set of changes to the Fallout.ini and FalloutPrefs.ini files that improve the game graphics when using higher end systems. The video demonstrates the advantage of each change. These changes are recommended for sufficiently capable systems; Fallout 3 is not very demanding for graphics so many systems should be able to use these INI values.

Some Additional Informative External Resources

These might also have some useful tips, but note that they have not been updated in a long time and might contain some erroneous material.