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   Home      iRacing-Help      DirectX_11
iRacing DirectX 11
iRacing deployed 2016s2. Updates below.

Share an easy link:
  • From 2016s4 release-notes: (older updates further down page)
  • DirectX 9

    - Our support for using DirectX 9 as the graphics system used by the simulation is winding down. If you are currently using DX9, your selection will be changed to DX11 one time upon installing this build. If you run into issues using DX11, you should work with our support team at to resolve them, as we will not be implementing new graphical features on DX9, and will eventually remove the ability to use it altogether - quite possibly as soon as the December 2016 build. For now, you can switch back to the DX9 version of the simulation, if needed, by opening the tools panel on the central navigation bar on the web site, and disabling the use of DX11. Again, you should work with support to resolve any issues you encounter with DX11, as the option to fall-back to DX9 will not remain forever.

    DirectX 11

    - Support for three screen surround rendering using NVIDIA Simultaneous Multi-Projection (SMP) technology has been enabled for GPUs that support SMP.
    - - To enable this feature you must configure three monitors as usual, enable the Multi-Projection option (previously named "render view per screen"), then enable the new SMP option. All of these options are located in the top area of the Graphics Options screen.
    - - Due to some limitations with the NVIDIA SMP surround technology at this time in DX11, the maximum supported side screen angle is clamped to 45 degrees, and the maximum field of view is clamped to 160 degrees. Beyond this the SMP warping can malfunction. NVidia is working on a solution for this.
    - - A few of the Simulator's subsystems still require compatibility fixes to operate correctly with SMP. Therefore, in this early version, when SMP is enabled, some other systems must be adjusted for compatibility: Particle Detail is set to Low, Dynamic Night Shadows are Disabled (Shadow Volumes still work), and Depth-of-Field effects are Disabled.

    - A new night shadowing system, Dynamic Night Shadow Maps (DNSM), has been implemented. It is activated by enabling the "Night Shadow Maps" option. This system works more like the sun shadow maps during the day time and should have similar performance. By default the system chooses the "best" three lights and projects those shadows into the scene. The shadows for these lights will fade in and out as new lights are automatically selected as the "best" sources.
    - - The options for this setting are as follows:
    - - Global Options (both driving and replay):
    - - - DNSMMaxLightsPerPass=3 ; 0-6 = Shadowing lights per-fullscreen pass
    - - - - How many shadowing lights to render per-pass. Lower numbers may be faster for lower end hardware.
    - - - DNSMQuality=2 ; 0 = 512x512 1 = 1024x1024 2 = 2048x2048 3 = 4096x4096
    - - - - This controls the size of the shadow maps. Lower numbers are worse quality but render faster.
    - - Mode Specific Options (driving or replay only):
    - - - DNSMEnable=1 ; 0 = off 1 = dynamic night shadow maps
    - - - - Enables or disables the night shadow maps for this mode.
    - - - DNSMTSOsCastShadows=1 ; 0 = off 1 = track objects cast shadows
    - - - - This will cause track objects (pit objects like signs etc) to cast shadows as well as cars.
    - - - DNSMWallsCastShadows=0 ; 0 = off 1 = track walls cast shadows
    - - - - This will cause track walls to cast shadows.
    - - - DNSMHeadlightsCastShadows=0 ; 0 = off 1 = car headlights cast shadows
    - - - - This will cause car headlights to cast shadows.
    - - - DNSMShadowFade=50 ; 0 to # = time for night shadows in 100ths of a sec to fade in and out (50 default)
    - - - - How long it takes for shadows to fade in and out. Lower numbers mean less time and shadows will "pop" more but look darker. Higher numbers mean you will see less popping but shadows will typically appear less dark initially.
    - - - DNSMFilter=2 ; 0 = none 1 = Fetch4 2 = PCF4
    - - - - The kind of filtering to apply to the shadows. We especially need testing with level 1 as it is not supported by all DX10/11 level hardware. Higher numbers mean shadows will look better but will be more expensive to render.
    - - - DNSMNumLights=3 ; 0 to 128 = Max number of shadow mapped lights at night
    - - - - How many shadowing lights to render every frame. This will perform multiple passes based on DNSMMaxLightsPerPass in order to render all of the lights. It will only render the number of lights actually required so if you set this to 100 but there are only 5 lights in the scene it will only render 5 shadows.
    - - - DNSMDownsampleFirst=0 ; 0 = per-AA-sample shadows 1 = per-pixel shadow
    - - - - This determines if we do shadows per-pixel or at every AA sample in the buffer. Setting this to 1 may be faster, especially if you have a large number of lights enabled, but will result in slightly lower quality.

    - Fixed the flickering static shadow maps when AMD Crossfire is enabled, and improved the compatibility/performance of both AMD Crossfire and NVIDIA SLI. For these changes to take effect, you must manually set the "Number of GPUs" in the Graphics Options screen and restart. This setting is stored as "NumMultiGPUs=" in the "rendererDX11.ini" file. Setting the number of GPUs higher than needed will waste video memory as some graphics resources are allocated per GPU.

    - In the Graphics Options, the "Max Prerenderered Frames" option will now be disabled when the "Number of GPUs" option is set to a value of 2 or greater. This is because frame queries are not accurate in these cases.

    - In the Graphics Options, the windowed "Border" option will now be disabled when the "Fullscreen" option is enabled. This is because the "Border" option has no effect in fullscreen.

    - Reduced the magnitude of the delay when entering and exiting the car at night tracks.

    - Disabled incorrect self-shadowing on cars at night tracks when Shadow Volumes enabled.


    - Fixed an issue where dust clouds were appearing where no cars were driving.


    - The wind now procedurally animates the flags on some tracks including:
    - - Barber Motorsports Park
    - - Circuit des 24 Heures du Mans
    - - Circuit de Spa-Francorchamps
    - - Circuit of the Americas
    - - Daytona International Speedway
    - - Five Flags Speedway
    - - Indianapolis Motor Speedway
    - - Mid-Ohio Sports Car Course
    - - Road Atlanta
    - - Talladega Superspeedway
    - - Watkins Glen International

    - The Patrouille de France will now be performing fly-overs at Le Mans.

  • From 2016s2 release-notes: (updates further down page)
  • DirectX 11

    - A preliminary “beta” version of a DirectX 11 based version of the Simulator is now available for testing and is provided via two additional executables, a 32-bit version named “iracingSimDX11.exe,” and a 64-bit version named “iRacingSim64DX11.exe.” You may select to use either the DirectX 9 or DirectX 11 version, as well as choose between the 32-bit or 64-bit version of the Simulator using the “Settings” page of the member site. We recommend using the 64-bit version if possible.

    - The Graphics Options settings for the DirectX 11 version are stored separately from those for the DirectX 9 version; they can be found in the “rendererDX11.ini” file. This file will be created automatically after launching the DirectX 11 version of the simulator for the first time, which will also initiate the auto-configuration process.

    - The configuration options for the DirectX 11 versions, including the resolution and refresh rate as selected during the auto-configuration, are stored in a new section of “app.ini” file named, “[Graphics DX11].”

    - Please note that when setting up any application overrides in your GPU’s device driver’s settings to take care to set them for the correct executable name(s).

    DirectX 9

    - Added a new option to the "renderer.ini" file named, “ReduceCockpitFlicker,” which is enabled by default. This option reduces the z-fighting and flickering between objects that can sometimes be seen in vehicle cockpits while racing at very large tracks.

    - Fixed an issue with the rendering of fog over the Dynamic Track, which occurred when rendering the Dynamic Track as a separate pass via the setting in the “renderer.ini” file.

    - The flare intensity of headlights has been reduced during the daytime.

    - Fixed several issues with physically based rendering at night tracks.

    - Fixed an issue with shadow maps that caused some of them to periodically render using incorrect texture sampling.


My first look:
  • By default we are still running DirextX 9.
    Because I didn't know what DirectX 11 would do:
    Take a screenshot of existing graphic settings.
    I copied the root files from /documents/iRacing/ to a safe place.
    I later deleted the new files and put the old files back when I turned off DX11. 
    If you read the forum (and some notes further down), it isn't smooth sailing for everyone.

  • To enable DirectX 11 > Member page > settings > toggle the switch

  • After enabling DirectX 11:
    I ensured I copied the root files of documents/iRacing/ to another folder
    Opened a TEST session
    Answered the graphics wizard - selected my card and setting 5760x1080
    Opened options > GRAPHICS tab > re-entered my previous monitor settings

  • NOTE: if you are tweaking your graphics cards' software, select the correct file:
    32-bit dx9 = iRacingSim.exe
    64-bit dx9 = iRacingSim64.exe
    32-bit dx11 = iRacingSimDX11.exe
    64-bit dx11 = iRacingSim64DX11.exe


From staff post (Dave G 4.2.16):
  • MipLODBias=0
    "This controls how much we bias the texture mip map lookup. If you set it to 100 we will choose a 1 mip map lower than the default level causing the textures to become blurrier but alias less. If you set it to -100 we will choose one mip level higher than normal causing textures to look sharper but alias more. You can go higher than 100 or lower than -100 which will cause us to skip even more mip levels. It expects integer values so 1, 2, 10, 100, -1, -2, -100, etc."
  • WorldNearPlaneDistance=10
    "This controls how far we push out the near clipping plane on the camera for track geometry. At it's default anything outside of the car will be clipped at 1 meter. This helps with the z precision issues (seen at Nurburging where you see a lot of Z-fighting/shimmering). The higher the number the further out we'll push the clipping causing slightly better precision (less shimmering), but possibly cutting off parts of the track. Depending on the car you are driving and your field of view you could potentially push this out further. If you have high FOV or are driving an open cockpit car, you might want to pull it in closer to prevent any nearby track/objects from being clipped. "
  • ShaderQuality=2
    "Shader quality 3 is an experimental mode. It currently only has an impact at night tracks, where instead of the faked reflections, the sim will render with 8 per-pixel lights based on the nearest lights around the track. We didn't get enough time to test the performance implications or the visuals at very many tracks so it is "hidden" from the UI."

iRacing THREADS:
Anyone offering a good tutorial for Dx11?
Any good threads I should add to the list below? Contact.
Other than the quick test above, I know nothing about Dx11.
  • DX11 fix for AMD Users thread.
  • nVidia users, keep an eye on Jacob's Guide: iRacing Graphics Options and nVidia Setting thread for updates.
    Jacob's recent post:
    "DX11: 8x AA, 4xSS TR AA  means
    When using iRacing on DirectX11,
    - Set in-sim Antialiasing (AA) to 8x
    - Set NVIDIA Control Panel Antialiasing to Application-Controlled
    - Set NVIDIA Control Panel Transparency Antialiasing to Supersampling (SS), at 4x.
    I will update the guide eventually. I swear."
  • DX11 and SweetFx suggestions I've read:
    - A staff post: "Try disabling the video capture in app.ini if having issues"
    - A member post says: "If you were using SweetFX previously you may need to go into the iracing folder and delete d3d9.dll and dxgi.dll"
  • Looks like a thread of DX11 application errors with staff helping.
    Staff post; Randy C:
    In your graphics card manufacturer's config settings, you might need to specify particular options based on the name of the program file that is being executed.
    The different versions of our sim (32- or 64-bit, dx9 or dx11) are in different executable files.
    32-bit dx9 = iRacingSim.exe
    64-bit dx9 = iRacingSim64.exe
    32-bit dx11 = iRacingSimDX11.exe
    64-bit dx11 = iRacingSim64DX11.exe
  • Staff post; Randy C: When you use the Settings tab on the web site to select DX11, it should create a file in the simulation's installation directory (C:/Program Files (x86)/iRacing, by default) named _useDX11.txt
    The contents of this file dictate whether or not the DX9 or the DX11 version of the sim is launched. If there is a 1 in the file, it'll use DX11. If there's a 0 (or if the file is missing) it'll use DX9.
    Selecting 32- vs 64-bit works the same way, but the file is named _use64bit.txt.
    Both files are consulted to choose which specific version of the sim is launched.
    32-bit DX9  64-bit DX9  32-bit DX11  64-bit DX11
  • Staff post; Shawn N: "Shadow volumes are still a performance killer. We are hoping to eliminate them in dx11."
  • Staff post; Shawn N:
    "I think in general the dx11 version is requiring more video memory than the dx9 version. It may help on GPUs with 1.5GB or less of video memory to lower the video memory slider quite a bit to see if it helps.
    Also I'm not clear on the resource usage of the video capture system. It might be worth testing with it disabled in app.ini to see if it helps."
  • Staff post; Randy C: "Try disabling your screen saver while you're racing. Either that, or set it to not require a password.
    Apparently it's an issue in Win10 where it ignores our request to disable the screen saver." (Thread iRacingSim64DX11 error while driving).
  • Staff post; Randy C: "The fireworks are only displayed if the "Particles" graphics option is set to a value higher than "low'. Referring to the release notes, the patch forces this setting to "low" unless you manually change it, because using a higher setting caused the simulation to hang occasionally for some of our testers. That issue is being investigated."

  • 2016 S3 staff post; Shawn N: 

    We changed some stuff in the way the full-screen graphics modes are detected and utilized, if having any odd issues with full screen, re-running the auto-config (just delete the rendererDX11.ini file is one way to do that) will make you pick a new full screen mode from the new lists.

    If that doesn't help, running in a window is really a great option for DX11. You can do "fake fullscreen" by choosing a borderless window option during the autoconfig. 

  • 2016 Season 3 from release notes


    - The cubemaps for all tracks have been updated. This will cause much brighter reflections off of objects.

    - Post-processing effects have been removed from the cubemaps for all night tracks. This was useful in the past, but is no longer needed.

    - Fixed occlusion culling so that very large nearby objects no longer incorrectly disappear, especially in mirrors.

    - Fixed a crash that could happen when trying to draw a lot of cars in the world with headlights.

    - Improved the algorithm for updating Dynamic Track textures to ensure timely graphical updates.

    - The option, "DynamicTrackTextureUpdateRate," has been added to the "renderer.ini" file to control the maximum frequency of Dynamic Track texture updates.

    - The option, "ParticlesDetail," has been renamed to "ParticleDetail" in the "renderer.ini" file.

    - Hang logging is now disabled by default, but can be enabled in order to help us investigate issues.

    DirectX 9

    - Fixed a memory leak that occurred when rendering a Tech Track.

    DirectX 11

    - Tech Tracks utilizing direct laser scan data can now be rendered in DirectX 11.

    - Glowing light effects now interact more accurately with fog.

    - Ghost car now renders correctly.

    - The old spark system is now hidden if PopcornFX is active, due to the new PopcornFX spark system.

    - Adjusted the graphical autoconfig selection of default graphics modes to favor higher refresh rates and standard scaling modes.

    - Fixed several bugs with night lighting and high detail headlights, where DX11 could look significantly different than DX9.

    - Fixed an issue with track shaders when using "Low" Shader Detail.

    - Fixed an issue where random flickers of geometry could render along with some particles.

    - Fixed several issues related to the antialiasing of painted lines and other surface decals at both night and day tracks.

    - Fixed an issue where tire rims could appear white when using the "Low" Shader Detail setting.

    - Fixed the Sim's UI to correctly toggle between fullscreen and windowed cursor modes when the Sim toggles between fullscreen and windowed modes.

    - Fixed an issue where shadow volume geometry was being created at load time even when the "ShaderQuality" option in the "DX11.ini" file was set to 0.

    - If DirectX 11 fails to report a display mode, a fake display mode is created. This may allow the Simulator to operate in a windowed display mode or a fake fullscreen.

    - All new installations of iRacing will now default to DirectX 11.


    - All tracks now have complete particle collision, so particles such as dirt, sparks, and gravel can bounce along the surface instead of passing through the environment.
    - Fixed an issue where all dust was being rendered as black in the 32-bit version of the Sim.

  • 2016 Season 2 patch 2.2 from release notes

    DirectX 11
    - Added support for "centered" (letterboxed) and "stretched" graphics modes. When these are available, the options screen and the graphical auto-configuration screen will indicate these special scaling attributes along with each mode’s refresh rate. We also removed a previous attempt to collapse multiple graphics modes with very similar refresh rates into a single mode, and now simply expose all of the unique modes, as they can behave subtly different, and the differences can be important. If you are using DX11 in full screen, we recommend running the graphics auto-configuration after installing this patch to select a full screen mode again from the enhanced choices.
    - - KNOWN ISSUE: Currently when using Alt+Enter to return to full-screen mode from windowed-mode, DXGI may not return the Simulator to the originally selected full-screen mode. 

  • 2016 Season 2 patch 2.1 from release notes

    DirectX 11
    - Fixed an issue where shadow volume geometry was being created at load time even when the "ShaderQuality" option in the "DX11.ini" file was set to 0.

  • 2016 Season 2 patch 2 from release notes

    DirectX 11
    – Fixed an issue where the drop shadow of a car was sometimes rendered using the texture of a different car.

    – Fixed an issue where random flickers of geometry could be rendered with some particles.

    - Fixed some large pauses that would occur while loading due to shadow volumes.


    - We have worked with the folks at PopcornFX and fixed an issue where the Sim could freeze when the Particle Detail setting is at the "Medium" or "High" value. With this fix, please feel free to adjust the Particle Detail setting as you wish. If you increase the Particle Detail setting and start to experience application freezes, please try reducing it back to the "Low" value and contact Customer Support for advice.

    Staff post (4/2016)
    "We didn't change anything related to shadows that would cause something like that. There is a known issue where using DX11 and AMD crossfire together causes an issue that looks like that, where for some reason one GPU seems to have a different copy of the shadow textures than the other."

    See Alt-Tab

  • 2016 Season 2 patch 1 from release notes

    DirectX 9

    - Fixed an issue where windshield reflections appeared dimmer than in DirectX 11.

    DirectX 11

    – Fixed a crash bug that happened when exiting the simulator with certain graphics settings, such as class 1 settings with Render Dynamic Tires disabled.

    – Fixed a crash bug that happened when exiting race sessions launched from pre-race practice sessions.

    - Fixed an issue where track temperatures in DX11 were reported to be warmer than track temperatures in DX9.

    - Fixed an issue where skies were often not oriented correctly. For instance, the sun was often located at some random and incorrect position.

    - Fixed the odd bluish shadow patches that could appear on road surfaces and curbs with low sun angles such as occur during the morning and afternoon. The issue was noticed at Lime Rock Park and Virginia International Raceway.

    – Fixed an issue where shadow volumes were not utilizing the optimized “shadow models” when available. Lit dashboard displays no longer cast unnecessary shadow volumes.

    - Fixed an issue where black lines would sometimes appear when using "High" Shader Quality.

    - Fixed an issue where Track Surface Decals could tile incorrectly, resulting in odd patterns of lines seen on the track at Southern National Motorsports Park, and some other areas.

    - Fixed an issue where some tire rims were rendering white. Generally, these vehicles were not yet updated to be using the PBR Shader.

    - Fixed an issue where chrome could render too bright on some of the older car models.

    - Fixed a framerate issue with low res particles.

    - Fixed lighted dash displays clipping with the wheel.

    - Mirrors now support low detail mode; previously they always rendered in high detail mode.

    - The filter that removes resolutions smaller than the desktop dimensions in the Autoconfig application has been removed.

    - The simulator now attempts to keep activation, and not minimize, when losing window activation, unless an Alt+Tab function was recently processed. This may help prevent "pop-up windows" and notifications from minimizing the simulator.


    - As a precaution against a known issue with application freezes that may occur when Particle Detail is set to the "Medium" or "High" value, the Sim will reset your Particle Detail setting to the "Low" value the first time it launches.

    - Opponent vehicles will now emit dust particles correctly.

    - An issue with black particle debris effects on tires has been fixed.

    Dynamic Tire Debris Accumulation

    - Fixed an issue where tires would appear black when the Particle Detail option was set to the "Low" setting.

    - This system will be disabled when the "Shader Quality" is set to "Medium" or lower.


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