FSX/P3D OOM (Out Of Memory) helper/fix

Dear Simmers,

As we get more and more plagued by OOMs in FSX due to 4GB constraint, there is a Microsoft fix that apparently helps to prevent an OOM happening in both P3D and FSX.

Beware that this is not a FIX to prevent OOMs altogether, it only helps a bit. FSX/P3D will finally crash if you keep on using the sim.

Until now there are no adverse effects on using this “fix”.

Link to Microsoft fix.

Just download and install the “FixIt”.

It will change the heap limit.

The default being:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems


and the FixIt is going to change the 768 to 1024.

Here is a screenshot also showing where this is exactly located:

This is only for x64 version of Windows 7.

My thanks go to OmniAtlas for posting this!

This entry was posted in FSX Tweaking. Bookmark the permalink.

63 Responses to FSX/P3D OOM (Out Of Memory) helper/fix

  1. Jack J Jackson says:

    Hm, I don’t even have that line in my Registry! Yes I have followed the link, run the program from Microsoft, restarted my PC, but….. still no SharedSection entry. Yes I have a Win7 HOme Premium 64.bit version.

    the Swede in Spain

    • Kosta says:

      Jack, this is explained very poorly, and also by me. I attached a screenshot showing the highlighted Windows key, in which SharedSection is in. I hope that clarifys it better.

      • Jack J Jackson says:

        Thanks Kosta, that did clearyfy everything. If the column is too narrow it’s possible to widen it to see the whole text!!! ;-))))))))

  2. pazzini says:

    Thanks for letting me know…
    However, by adding heap size doesn’t fully solve the OOM problem.
    If the OOM culprit is still in the FSX, then sooner or later, the OOM will happen.

    • Kosta says:

      Of course. IMO, it helps, but just a little. Not much. If you have OOM problems, a serious ones, then this will surely not solve them. It might prevent one or another OOM though.

  3. KJAc says:

    I’ve got to ask, but first allow me to offer my shear gratitude for your efforts to relieve us even marginally of this annoyance. Back to my question; where is Microsoft in all of this????? It’s probably been asked 100 times over. Oom issue seems to be analogous with the car, carburetor and gas in that we will always need to buy (gas) hardware/components to run FSX

  4. KjAc says:

    Acknowledged …but on a good note… just completed a successful trip from heavy fps hitter (AS) Nice LFMN to Copenhagen EKCH (Scansim) and no digs flying Airbusx extended. FSx slowed to its traditional FPS on arrive but no digs and I’m happy to report no Oom notice. Onto the next test as this has been a know area for Oom messages…next stop Uk2000 EGLL / Orbx EU. Thanks Kosta. Fix appears to arrest the potential situations as you suggested. Lets hope for a continuance of the same…

  5. KjAc says:

    WOW!!!! aside from a 7 sec pause btw EGLC and EGLL no dig no Oom message..I’m a believer:) and a happy one at that. Landed at EGLL (UK2000) with traffic setting at 66% and 35% GA, cars 22% boats at 18% (both); Orbx EU, UTX with night lighting, EGLC (UK2000) autogen at very Dense, AS2012, REX Essentials , and airbusx extended AND NO Oom…yeeeeeeeeeeeesssssssssss…next big test EGLL to FSDT KJFK with AS cities NYC. you intimated this may help a little…so far it been beyond that. The next test will really put a nail on it for me…crossing the pond from heavy scenery to heavy scenery after several hours. I think I’ll aim for the Pmdg 747..I’ll let you know

  6. KjAc says:

    ok that was pretty arrogant/audacious of me. Hit a CTD 30 miles out…mind you I paused FSX for about 30 mins too.

  7. Kosta says:

    CTD or OOM? – there is a difference. Pausing FSX doesn’t have any impact usually.

  8. KjAc says:

    Runtime error to be exact…(somethime new) tried to ignore it and continued on with FSX but than the Oom message which this time froze FSX completely…

  9. KjAc says:

    oops (something new) that is

  10. Herbert Krosta says:

    Thank you for the info and link. Hello Kosta, How can I show you some Screenshot of my settings in here? I fly from KHQM (Bowermans field) 30 FPS towards Seattle. Near Seattle 18-20 FPS, I have a GTX 560 tweaked the GPU clock 810 to 950 MHz and i5 2500k @ 4.632 GHz Herb

    • Kosta says:

      If you want to show me some screenshots, the best way is to host them somewhere, like Dropbox. Just register, put into public folder and post a link.
      You know Seattle is probably one of the hardest scenarios for FSX, so 18-20fps do sound reasonable to me?
      Overclocking the GPU can in fact someone have adverse effects on FSX.
      Awaiting your shot.

  11. Herbert Krosta says:

    I would like to show you my CP Memory too. I don’t get error, but I do see a 48% most used figure. Is this good? Here are the Specs: My Memory “Kingston Hyper” 2×4 GB
    Dram Frequ. = 824.3 MHz
    FSB Dram = 1:6
    CAS# latency = 9.0 clocks
    IRCD = 9.0 clocks
    IRP = 9.0 clocks
    IRAS = 27 clocks
    Command Rate = 1T

    • Kosta says:

      What is your speed for DRAM in the BIOS?

      • Herbert Krosta says:

        In my BIOS it show: Total Memory 8192 MB DDR3, Memory Frequency 1648 MHz
        Target CPU Turbo-Mode Speed 4532 MHz, Target DRAM Speed 1648 MHZ.
        17-20 at KSEA fly-bye. My question: Do I need different Memory for my ASUS P8 Z68-V Mobo? Herb

      • Kosta says:

        OK, so you are running your mem at 1648. That is in general quite low coupled with CL9. The optimal FSX memory is 1666@CL6-7 or 2133@CL9. Otherwise RAM is a bit on the low side.
        You should check what your specs for the RAM you have are, do you REALLY have 1600@CL9, because that is hard to believe.
        You should be running XMP profile in your BIOS for the RAM.

        To answer your final question, I need the info what memory you have now. Exact specs, name: best open the CPU-Z, SPD page, select slot in which memory is inserted and write me the exact Part Number.

  12. Herbert Krosta says:

    Kingston, Part# KHX1600C9D3/4GX Serial# 671A1B85
    I do see here a entry: SPD Ext. XMP on the right side in the SPD page. Does that mean I’m running XMP in my Bios?

    • Herbert Krosta says:

      I found this statement:
      I am unable to manually overclock my system or use XMP. Is there any other way for me to overclock my system?
      Yes, Kingston recently introduced a new line of Plug & Play memory called HyperX PnP. Simply install your memory and reboot your system. The memory will perform at the higher advertisede speed without increasing your voltage.

      Hello Kosta, I do have HyperX installed. Thank you for your help. I was thinking that a drop of 13 frames is a little to much. Sometimes clouds reload or a see a spike like lightening, even when 30 frames showing at the screen. Herb

      • Herbert Krosta says:

        I would like to Add: I removed the [BufferPools], UsePools=0, entry from FSX Confg. and test flight same as before. After take-off 30 FPS till near KSEA there it go down a little 25 FPS at Landing I had 18-20 also at Runway. Taxing to Parking, went from 20-24 and at Parking, Engine shut, Light out, 25-26 FPS. view out Cockpit seeing some car traffic go by. This maybe the best for ORBX and KSEA. A cloud reload has happen twice at that flight. You may remove most of my post, I just sneaked in here with my troubles.

  13. Kosta says:

    OK, your RAM is then running fine.
    But about the BP=0. It’s a very sensitive trick for FSX, as I already noted in my guide. You need to meet specific requirements, and putting too strong CPU ontop of weak(er) GPU, it could be that you run into troubles (I forgot, which GPU do you have?). BP=0 simply requires a strong GPU, because it omits the bufferpool. I would quite much bet that when you see that drop of FPS, that your GPU is running at 100%, meaning the system, or the settings are not balanced well. GPU should always be “above” CPU when it comes to performance.
    Having said that, I’m glad you found the configuration that works for you, Herbert!

  14. Herbert Krosta says:

    Hello Kosta!
    I did test-fly Cessna172 1500 feet to KSEA. EVGA nVidia GTX 560 1924 MB DDR5 My GPU-Z show 47% max the most. Here is something new: while I’m in here, I had 2x a blue screen : Report
    Problem signature:
    Problem Event Name: BlueScreen
    OS Version: 6.1.7601.
    Locale ID: 1033

    Additional information about the problem:
    BCCode: 124
    BCP1: 0000000000000000
    BCP2: FFFFFA800798C028
    BCP3: 00000000BE200000
    BCP4: 000000000005110A
    OS Version: 6_1_7601
    Service Pack: 1_0
    Product: 768_1

    Files that help describe the problem:

    Read our privacy statement online:

    If the online privacy statement is not available, please read our privacy statement offline:

    • Kosta says:

      Your CPU voltage is too low.

      • Herbert Krosta says:

        Do you mean the Incoming 110 Volt, or Power-supply. I have OCZ 500W MOD Xstream-PRO 80 plus PSU. 25amp @ DC+5V and +3.3V, 18amp @ + 12V1 and +12V2. rails. Did the PSU got weak over time? Under my desk, power-bar Computer, Monitor LG, Saitek Joystick and Peddle, Set Stereo speakers, run this for long time with no problem.

      • Kosta says:

        No, I mean the Vcore for the CPU, which is set in the BIOS.

        I would recommend you open a thread on flightsim.com, I’m losing perspective already with you, as I can’t just scroll up and see what you wrote me. Blog was never intended for this 🙂

      • Herbert Krosta says:

        CPU is set to AUTO in CPU-Z it varies from 0.992v to 1.360v Do I have to set a constant voltage in BIOS and what value?

      • Kosta says:

        Bad. Vcore should never be set to auto. But right now, I don’t know what your frequency is.

        As said, open a thread, put all the info there, which hardware, software, bios settings, overclock settings, let us just take a look at it there.

  15. Herbert Krosta says:

    Thank You Kosta for your help, I will go to Flightsim next week. Please Delete all my posting in here. Herb

    • Kosta says:

      No need Herb. Just wanted to say that your problem will be easier to follow on a forum of some kind, rather than here.

  16. Vidan says:

    I have 4GB DDR3 RAM, will it help on my PC?

    • Kosta says:

      With FSX, under the 64bit OS, you should have 8GB of RAM.

      • Anson Cheung says:

        I am now having 4GB ram with 64bit Windows 8.1 unfortunately facing OOMs, should adding physical ram to 8GB help?

  17. jaggy says:

    check this site out. it totally fixed my OOM issues http://www.ntcore.com/4gb_patch.php I went to seatle with sliders all maxed a place where i always run out of memory in orbx and also i tested it flying from darrington to Cushman Meadows this tool allocates more memory to 32 bit applications (which is what fsx is) within 64 bit operating systems which is what we are all using these days. i put fsx into windowed mode and watched how much memory fsx was using in my task manager and what do you know 2 minutes of flying over seatle and i had gone over two gigs of memory.
    problem sorted.

    • Kosta says:


      Very old news. Besides, this is something FSX already has. You can’t allocate more than 4GB for FSX – you just can’t. This tweak only make the application large address aware, which FSX already is.

      If you have the problem noted, then I reckon you are running 32bit OS, which you shouldn’t be running with FSX anyway! 64bit is the way to go, and you will automatically have 4GB VAS available to you.

  18. jaggy says:

    No i am running 66 bit, have been for years all i can say is that i was getting errors and now after adding fsx exe to this program im not.

    • Kosta says:

      Jaggy, thanks for the info, however this is one thing I will practically refuse to believe, since long ago I was using this, the last was with FS9, but then also tried with FSX, and FSX *will not* use more than 4GB of VAS. Also this tweak will not cause an addon use less memory. If you have a proof of that, I urge you to provide it, otherwise I must stand with my opinion, as this would be way too misleading to many users.

  19. jaggy says:

    sorry obviously typo there 64 bit

  20. jaggy says:

    P.S And i am not the only one. four of the guys i used to fly with have moved over to P3D and they were all having OOM issues this fix has stopped all of their problems. And there all running 64 bit systems.

  21. Boaz says:

    I recently began to see OOM. Before it was only FSDT YVR and Flytampa YUL that caused OOMs, but now I see it also at LAX and IAD.

    I blamed FSDTs addon manager, because it started happening after I had buildings disappearing, then uninstalling and reinstalling the addon manager helped with this problem, but somehow caused this… Dunno what to do or think

    • Kosta says:

      What to think: it’s not an addon manager, it’s very wrong to think that an addon manager from FSDT can cause OOMs (actually, it can, but the app footprint is so small, that it’s just a drop of water into the sea).
      Read my article and understand why OOMs are happening!

  22. The Dad says:

    Wooah, this totally resolved the severe OOM issue I started just recently even in standard FSX planes and average airport addons. I expected to embark on a long journey with analyzing the Windows updates and recent FSX setting changes made by new add-ons….

    This simpe fix did the trick. Thank you!!

    Mind you this does not resolve all OOMs of course. The hard limits are still there. But it returned me back to a controlled flight environment where I can predict what will happen under which circumstances.

    I greatly appreciate your work Kosta! Your deep inights have helped me many times.

  23. Pingback: Anonymous

  24. Formiga says:

    I had a problem recently. “failed to read from file” it happens at various stages of flight.
    Do you know what this is? What can i do to solve this situation.
    Thanks a lot

    • Kosta says:

      Not quite enough to go with.
      First thing that comes in my mind is faulty disk or becoming faulty. Run checkdisk and see if it finds something…

  25. Matt says:

    Hi, I just upgraded my memory and video card and I’m now getting oom crash. Went from a 560ti to 780 and 8gb 1333 to 16gb of 1600. I haven’t changed any settings and it worked fine with the old stuff. Tried the MS fix you linked, OOM went from about 5 minutes to every 15. Win 7 64bit, oced 2500k @4.2

    • Kosta says:

      Without precise and correct measurements before and after in same scenarios with same settings, there is no viable data or comparison. Thus saying “I just upgraded my memory and video card and I’m now getting oom crash.” is without meaning really.
      There have been reports of newer cards with more VRAM using more VAS, but I am yet to see the proof. By that theory, running 6GB Titan shouldn’t be possible with the FSX… in any case, good luck, there is nothing much I can do except to tell you to manage the FSX according to my guide and OOM guide.

  26. Matt says:

    I think I’ve figured it out. My paging file was set at 3Gb. Changed it to let windows manage and its now 16Gb. I did not change anything other than the paging file. Had a successful 3 hour flight with the same scenery (fly tampa KMIA and photo real Florida) and aircraft (pmdg 737) .

  27. Otto says:

    Well, this Fixit made my whole windows crash. I call it “bad luck” but I’m not touching this thing again. I was able to run in safe mode to transfer important files before doing a fresh install of EVERYTHING including the OS.

    • Kosta says:

      Indeed bad luck. The fixit changes the one registry setting only. Reverting to the default would have fixed the problem, if Fixit “broke” your computer.

  28. Otniel B. OCampo says:

    Does this Fix works with FSX-SE?

  29. Jordan says:

    Does this work for windows 8.1?

  30. Chris says:

    @ Jordan

    Just install: Right-Klick = Properties = Compatibility = “run this program in compatibility mode for:”

  31. Brain Maxima says:

    It’s very effortless to find out any topic on net as compared to books, as
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  32. Well I had to follow the manual “Fix it yourself” instructions because this “Fixit” is no longer available for download. As per standard with anything Microsoft, they give you a cool blue “DOWNLOAD” button, which you click, which instead of downloading anything takes you to another list of stupidly unrelated articles with no downloads at all. Typical Microsoft.

    The GOOD news is that for even a beginner with no computer experience, the instructions are still there and regedit is easy to use. Just wish they’d remove the download link instead of sending you chasing unrelated articles thinking you are somehow getting a download.

  33. Marc I. says:

    Can the registry line be added in Windows 10 x64? Because it’s not there… Thanks 🙂

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