Hello guys! We all know that tuning Skyrim is a mysterious and sometimes tedious ordeal, especially considering when there are tons of guides around and every single one usually seems to contradict the next. And that one says the total opposite of the one you read just the day before.
In the todays article, we want to share with you some *not so commonly discussed*, but very useful tweaks we took note of during the past fourteen months of RCRN development!

1 – Memory Optimization

Bethesda released the “4gb patch” more than 8 months ago, but this doesn’t really matter, it was just a LAA fix in order to allow the properly handling of memory under 64 bit systems. But this doesn’t necessarily mean your system will automatically use more than 4gb of RAM!

In order to tell to Skyrim your correct amount of system memory you have to apply the following tweak:
Open your Skyrim.ini, usually located at the path: C:\Users\youruser\Documents\My Games\Skyrim and search for the line under the [Papyrus] section:


Then change the value marked as “*******” with the approximate amount of your system memory, by consulting the tab below:

if you have 4GB of ram -> iMaxAllocatedMemoryBytes=2000000000

if you have 6GB of ram -> iMaxAllocatedMemoryBytes=3000000000

if you have 8GB of ram -> iMaxAllocatedMemoryBytes=4000000000

(if the line is not there, simply add the appropriate line *only one choosing with your systems RAM amount)

This tweak usually helps really a lot, we found that the game is about 20% smoother when the properly memory value is set!

2 – Float Point Render Target (bFloatPointRenderTarget=1)

A lot of guides around the web advertise to keep this value to “0”, this is a common misconception. Advanced lighting mods like both RCRN and ENB actively use this settings and they require it set to “1”, keeping it disabled doesn’t provide any advantage, only issues. As can be seen in the example below:

The purpose of this setting is providing a more accurate lighting by using floating point verc’s/points instead of only int values.
In order to properly set this value, open your Skyrimprefs.ini, usually located at the path: C:\Users\youruser\Documents\My Games\Skyrim and set the following line:


Note: This fix is not useful with low tech CK only lighting mods, like cot or rlo/rlwc, because they cant play with float values!

3 – Flickering Light Distance (fFlickeringLightDistance=8192)

In vanilla Skyrim there is an annoying issue that often makes light sources like braziers or torches looks dim unless you move near them, this is also known as the “lights pop-up” bug.
It’s mostly caused by an engine issue, but it can be easily avoided by setting:


in your Skyrim.ini under the [General] section!

4 – Get rid of the useless .bmp Screenshots (bAllowScreenshot=0)

When you are running a lighting mod that has his own screenshots management and uses the “stamp/print screen” key on your keyboard to take them (like RCRN for example), you will encounter a “screenshot duplication” containing a screenshot of the vanilla image. To eliminate the wasted clutter caused by the generation of a .bmp screenshot when creating the proper .png shot, make the following edit:


in your Skyrim.ini under the [Display] section, you will block the useless .bmp generation, keeping only the .png shots containing the RCRN effects of the on screenshot!

5) How to fix the blocky shadows and the laggy shadow cycle

Along with every single Skyrim user, we have also fought versus those horribly blocky shadows.
After some tinkering we finally found a combination of settings that pleased us, here is what you have to edit in your SkyrimPrefs.ini:
















in the screenshots below you can see our fixes in action:

Note: this fix also helps in reducing the “shadow striping” problem.

Additionaly we also took care of the “laggy” shadow timecycle, this 2 settings when added under the [DISPLAY] section of your Skyrim.ini will make the shadow transition much smoother!



Here we finished with our 5 cents, we hope that they can be useful to you and that they can enhance your gameplay and push it even further!




  1. January 27, 2013  10:56 pm by ramakgaming

    iShadowMapResolution is listed twice, other than that - thank you for this!

  2. January 27, 2013  11:10 pm by joshezzell

    Question, what if I have 16GB of ram? Should it be set to 'iMaxAllocatedMemoryBytes=8000000000' ?

    • January 27, 2013  11:28 pm by aLaaa

      as far as we know 4000000000 is the limit, and we haven't found any benefit in pushing it higher!

      • March 20, 2013  4:07 am by noobzor

        4000000000 is way over the limit for this variable. As others may have pointed out, this variable is a 32-bit signed integer, which means that the maximum value is 2147483647. If you set a value higher than that, and then check the Papyrus logs, you will see that the value has rolled over to a negative number.

        • March 26, 2013  7:35 pm by Ravenous Raven

          If you have a 64-bit OS with 16GB of ram what should I set it to?

          • April 16, 2013  8:54 pm by wanderer000

            The number that he gave, "2147483647", is the highest possible number. Those with 8GB of RAM or higher should use that.

  3. January 28, 2013  7:05 am by klearlyc

    Thank you for the memory tweak. I always knew that patch wasn't sufficient but googling for the tweak command didn't help. Just for that one helpful hint you're the most awesome people in my book.. Forget the mighty fine smooth lighting and visual mod that prolly took infinite amount of time to tweak and test. Nah that pales in comparison. A BIG Thank you!

  4. February 3, 2013  11:19 am by k2_8191

    Thanks for sharing info. I've never heard the key "iMaxAllocatedMemoryBytes" exists! I'll try playing with that.
    Can I ask you some questions about the ini tweaks you mentioned?
    1. What does the key "iShadowMode" configures?
    Googling it gives some possible value (looks like 3, 4 or 5), however I can't find any further info for it...
    2. What is the differences among the keys "iShadowMapResolution", "iShadowMapResolutionPrimary", and "iShadowMapResolutionSecondary"?
    Seems they specify resolution of different kind of shadow, but there is no page explaining the difference in my scope.

  5. February 7, 2013  5:24 am by louisseife

    Thank you so much for sharing such awesome ini setting!
    Will give it a try and see what magic awaits. No doubt bout a result since you guys are true expert in this!
    RCRN has been making my Skyrim so much more enjoyable! Thanks again for your great support as always. Keep up the great work guys!!

  6. February 14, 2013  1:02 am by soundcreepy

    Tried using the shadow sharpening settings and the main thing I noticed when I move I see an annoying line where the blurred and sharp shadows meet, and if I increase the shadow sharpness, or decrease the blurring I guess, I get odd shadows everywhere. Ah well, your other tips work perfect so I'll survive, hehe.

  7. February 24, 2013  8:35 pm by Ghanima Atreides

    Thank you very much for these, they have been very useful! :D

  8. March 4, 2013  5:50 am by ShaggY

    Don't "fSunShadowUpdateTime" and "fSunUpdateThreshold" go into Skyrim.ini rather than SkyrimPrefs.ini as stated in this guide?

    • March 16, 2013  12:19 am by Fiks

      Indeedy. Had to move these two tweaks to Skyrim.ini before they took effect. It's one of those tweaks where you have to really look for it to notice that it's working, 'cause otherwise it doesn't attract attention. Unlike the sudden lurch of the default shadows.

  9. March 11, 2013  4:27 am by k2_8191

    Looks like SkyUI 3.2 shows Error Code 4 error when iMaxAllocatedMemoryBytes is higher than 2,147,483,647 (2^31 - 1).
    Maybe a value over that is out of range of its applicable value (considering prefix "i" of this key).

  10. March 25, 2013  8:14 pm by DTX3

    Yep as above the SkyUI shows error 4 when you add iMaxAllocatedMemoryBytes=*******

    "Your Papyrus INI settings are invalid. Please fix this, otherwise SkyUI will stop working at some point."

  11. April 10, 2013  12:25 pm by samcoolrunner

    Hi guys, whit the injection of the iMaxAllocatedMemoryBytes the game is more fluid , as above, the skyui show the error 4, i had a crash just one time so for me is not a big deal but, there is a solution? in my case i use 6g .

    • April 16, 2013  8:56 pm by wanderer000

      2147483647 is the highest possible number. Do not use the number listed in the guide as that will result in the Papyrus error.

      • April 16, 2013  10:02 pm by aLaaa

        there is not any papyrus error, the limit is 4294967294, and there is an hige difference between 4294967294 and 2147483647.

        • June 20, 2013  9:50 pm by wanderer000

          Setting it any higher than that number gave me an error.

  12. April 16, 2013  10:04 pm by aLaaa

    Just to clarify:
    Well, that value is technically supposed to be a 32-bit signed integer, so it shouldn't go over 2147483647, the point stated in the article is that despite "what it should be" pratically it doesn't work as "planned". So currently there is a quite noticeable difference between setting it at 2000000000 and 4000000000. (higher values will be ignored).

  13. April 21, 2013  7:02 am by kimm

    iMaxAllocatedMemoryBytes does not do what you have assumed. These values make no sense, and are bad advice.


      • April 22, 2013  2:26 pm by kimm

        I did read your post - did you read the info from the CK that I posted?

        The problem is not with the maximum size of 32bit integers, but with sane values for what this tweak actually does. It does not set the total available memory for the game, but the size of individual stack frames. The default value is 75k! Values of 2147483647 for stack frames are crazy, and there is a clear warning that values much higher than the default 75k can cause serious problems.

        • April 22, 2013  2:55 pm by aLaaa

          Yes i did, a long time ago, along with millions threads about this subject over the official boards.

          We tested this stuff a lot during development, and currently we are 100% sure that there is a quite important difference (we were shocked too the first time we accidentally discovered it), I perfectly know that the setting is meant to be about the allocated stack frames, what i'm saying is that currently it doesn't work only so, and seems that it also mess with the ugrid generation.
          For example running an higher iMaxMemory value, when running also an higher uGrid value, totally removes the crashes when moving between cells.

          Anyway if you want to join our testing you are welcome, RCRN and also this website are community runned projects, and we always encourage our users in sharing their thoughts :)

  14. April 24, 2013  4:08 pm by legodude

    I'm having a little trouble here in my C:\Users\Liam\Documents\My Games\Skyrim in the Skyrim config file I can't find any of the above settings.

    • May 12, 2013  11:05 am by aLaaa

      for most of the previous tweaks you need to look into SkyrimPrefs.ini not into Skyrim.ini

  15. April 29, 2013  4:59 pm by Wilza

    When I add in the first one to skyrim.ini, the "iMaxAllocatedMemoryBytes=4000000000", I have infinite loading screens. I take that out and it works fine. I have also tried the smaller values and the other value suggested in the previous comments, "2147483647". I have 16GB RAM.

  16. June 13, 2013  7:15 pm by DTX3

    So what should it be for 16gb? No one has actually clarified that.


    • June 13, 2013  7:25 pm by aLaaa

      Which seems to be the limit.

      • June 14, 2013  5:44 pm by DTX3

        That's my issue. I get the message

        "Your Papyrus INI settings are invalid. Please fix this, otherwise SkyUI will stop working at some point."

        Should I still crack on and ignore the error? I don't get the error if its set at 2147483647

        • July 11, 2013  10:54 pm by Mookeylama

          i'd like to know this too. will SKYUI work correctly w/ the figure set to 40000000000??

          • July 11, 2013  11:44 pm by aLaaa

            usually you can simply ignore that warning

  17. August 2, 2013  7:02 pm by qqqbbb

    iMaxAllocatedMemoryBytes is not memory allocated to the game, its memory allocated to papyrus VM (scripts). Increasing it may increase performance but numbers suggested here are ridiculous. And dont forget that skyrim is x86 program so it cant use more than 3.5 GB of system memory.

    • September 17, 2013  11:05 am by aLaaa

      We tested this stuff a lot during development, and currently we are 100% sure that there is a quite important difference (we were shocked too the first time we accidentally discovered it), I perfectly know that the setting is meant to be about the allocated stack frames, what i'm saying is that currently it doesn't work only so, and seems that it also mess with the ugrid generation.
      For example running an higher iMaxMemory value, when running also an higher uGrid value, totally removes the crashes when moving between cells.

      Anyway if you want to join our testing you are welcome, RCRN and also this website are community runned projects, and we always encourage our users in sharing their thoughts :)

  18. August 27, 2013  9:42 am by norgob

    Awesome guide it realy help with that anoying jagged shadows but it didnt help with the stripping actualy got worse :( BUT i altered fShadowBiasScale=0.1500 to fShadowBiasScale=1.50 and the stipping was gone for good :P and no performence issues with this guide other then me loading is a bit longer but i can live with that since now the game is as it should be :P BIG THX to you guys at Rcrn
    btw do that flicking light distance help for the dawnguard/heartfire/dragonborn dlc's ? i havnt noticed anything about the light from torches pop up though (i got all dlc's installed) and it says in the desciption that it was for vannila skyrim so i didnt use that

    • September 2, 2013  1:57 am by iBeas7n

      No reason to go that low in quality with fShadowBiasScale. Juset set it to fShadowBiasScale=0.6000 and enjoy!

  19. September 2, 2013  8:51 pm by techstepman

    just to make sure and dont do something stupid.i have 16 gb of ram so what value do i use here iMaxAllocatedMemoryBytes= ?

  20. September 16, 2013  5:18 am by projectphotoking

    When I used your shadow fix it messed up everything very badly by this I mean...my FPS is now at 14 when it was about 35. Please tell me how to set it back to original. I stupidly didn't make a back up first. Thanks. projectphotoking@live.com

    • September 17, 2013  11:07 am by aLaaa

      hi, you can simply restore original values from the advanced graphic settings tab.

  21. January 7, 2014  3:14 am by yodatgucc

    After applying these settings i now get better FPS( not exactly higher framerates but much more stable and less stuttering) . So greate guide ! I guess just put up a warning sign in big letters that it works for 64 BIT USERS only with at least 8gb ram.

  22. May 20, 2014  4:00 pm by Mythoswolf

    Thank you for these tweaks. they really improved my game. I was having quite a bit of clipping issues that seemed to have disappeared after following this guide. Very Much appreciated!

  23. June 16, 2014  2:48 pm by Urukrama

    Thanks for all the work RCRN community has done! Great Work!

    But there will always be some minor issues like this one. I implemented and double checked all above tweaks and all works fine except 1.
    At first I had not rebooted like advised and after SkyUI error 4 followed a CTD. So I rebooted, restarted Skyrim, created new game for testing.
    I find it always nice to work from clean save. Got SkyUI error 4 again, clicked Okay and everything works fine.
    Only thing is I get the SkyUI error 4 every single time I (re)load a save which is quite annoying.
    My son (who save/dies/loads) a lot more then I do found it so annoying, and I agree, that I replaced value 4000000000 with 2147483647 again. So we wont get the SkyUI error message every single time you load a game. :)

  24. July 27, 2014  3:51 pm by chypil

    Great work it fixes everything, and it looks amazing just problem is when you go to the options in skyrimLauncher it says shadows are on Ultra, it looks amazing but it lags alot cause my computer is not that good, anyways its a good job i hope ill enjoy it soon enough i buy new computer

  25. October 31, 2014  11:39 pm by Chris HPZ

    Hey community, new user here. So I applied the tweaks as suggested above and indeed the shadows look so much better than they once did. Unfortunately, Skyrim did suffer some performance loss as well. I use Hialgo Boost for the benefits it brings to FPS. And before following this guide, I got around 30 - 40 FPS outside and around 50 - 60 FPS in interiors and dungeons. Now mind you, these FPS values are an average. There's been times when I'll be in some dungeon getting 60 FPS, and then a second later it'll drop down to 30 FPS. Can't really say that I know why, I just know it happens. To add to the dilemma of iMaxAllocatedMemoryBytes= "some value here", what is the highest we can go? I have 32 GB's of RAM on my computer, and I'm reading conflicting opinions left and right. Hey wasn't that a statement in this guide somewhere? hahaha. I started playing Skyrim when it was up to the latest version, 1.9.2 I think is the number. I assume this version has the 4GB patch already applied. If this isn't correct, please let me know.

  26. July 30, 2015  4:43 pm by GlassDeviant

    I just have to post this because a lot of people are being misled by this misinformation. This has spread all over Skyrim fansites and is just plain wrong!

    The first item advises the user to set the iMaxAllocatedMemoryBytes value to a ridiculously high value. Bethesda developers have stated unequivocally that the manimum value for this variable is a single signed 32-bit integer, or 2147483647 but that you should never, ever set Papyrus to this value. What the heck are you going to do, allocate 2GB to just the scripting engine and squeeze the game code into the 1.1-2.0GB of RAM left available for a 32-bit application like Skyrim?

    The default value of 76800 is plenty in a normal, unmodded game and you should never need more than 153600 (twice that value). Remember, this is only for script code, nothing else. Not graphics, not game code, just stack space for Papyrus to use to run scripts.

    • July 30, 2015  4:53 pm by aLaaa

      Don't take me wrong, your explanation is perfectly fine on the paper, but actually it doesn't work so in the game, if you check where the ram is actually reserved you'll figure out that for some reason Beth kept it shared and not limited to scripting, so the reserved ram will be used as well and there is a benefit.

      This is not how this setting was intended, just stating that for some reason it works so, however feel free to check your self.

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