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Skyrim fails to load a save that uses > 2GB RAM



Hey guys,


I've run into a problem loading a save where the game itself uses more than 2 GB's ram and was wondering if anyone else has had this problem. ATM I'm using ugrids 9, I have a core I7-3770K, 8 GB ram, a 4 GB 680 GTX video card, and 256 GB SSD. The mods I'm have installed atm are using the highest textures available ....


   Hi-Res DLC Optimized

   Blessing - Altar Descriptions

   Enhanced Distant Terrain

   Enhanced Night Skyrim

   Glove and Boots - Rodnix

   High Quality LODS meshes, normals, and textures

   HQ Milky way galaxy

   Lush Grass

   Lush Trees w/Vurts Comp. Patch

   Climate of Tamriel

   Royal Mage Robes

   Serious HD Tetexture

   Vurts Flora Overhaul

   Skyrim HD 2k Textures dungeons, landscape, misc, towns

   Skyrim Realistic Overhaul

   Static Mesh Improvement Mod

   Skyrim Distance Overhaul Beta

   Unread Books Glow



So if for example I load a save in town the game uses around 875 MB VRam and 1700 MB Ram, but when I step outside of whiterun for example the games ram usage goes to 1140 MB VRam and almost 2400 MB Ram. Now I can play just fine like this and have no problems. Its just that if I save the game while outside and try to load that save that the game ends up loading forever and windows says the game is not responding. If I watch the stats of the game while loading the VRam goes to about 650 MB and the Ram usage goes upto about 2263 MB. Any time I've had the system pass 2GB of system ram while in play it plays fine but if I save it where its using more than 2 GB's system ram it will never load and just hangs. I've even had this problem in the past when using defualt ugrids and a ton of mods, I just reduced the number of mods until system ram usage was below 2 GB's when outside. I was hoping someone could shed some light on this for me.... and that its not a game engine issue.




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Ah, thank you frihyland. I've done a bunch of searches but could not find this specific topic with save game as almost all my searches would turn up results about 2/4GB memory usage and the large memory addresable flag and such, which is why I finally posted. Thanks again.

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I just ran into this myself... not even using higher uGrids. It really annoys me that gigantic limiting flaws like this exist in a game released in 2011. 2GB of ram is nothing...


PS: I couldn't find where the Wiki mentions this particular issue... little help?


EDIT: I'd forgotten that turned AA up to 4x from 2x in addition to switching all my texture mods to maximum resolution (was using lite versions of landscape and clutter on the big 3 texture packs). Switching it back to 2x enabled the save to load fine. Sooo I'm guessing (hoping) VRAM limitation? I'm still using my 2GB GTX680s, but I've got 4GB cards in the mail.

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So after doing more research, I've come across a few forum posts that claim the VRAM and system RAM both count toward Skyrim's 4GB RAM allocation limit? That seems... terrible. Doesn't that mean that the higher VRAM your card has the more likely it is the game will crash (assuming you're using that VRAM)? That would suck if my new 4GB cards had a negative impact on my game...

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The way you worded it is not accurate. There are 3 separate issues that all interplay. Using Windows 7 and Skyrim as example we get:

  • From an OS/hardware viewpoint in x64 there is a hard RAM limit of 192GB, in x86 there is a hard 4GB limit
  • From a 32 bit application viewpoint Skyrim can only address 4GB RAM (without writing its own memory handler) and by default its 2GB (and its defacto 3.2GB because the OS uses the rest), 64 bit apps can address 8 Terabytes
  • VRAM is completely unrelated but it does seem to use regular RAM as a buffer, if you have 1GB VRAM in my experience it will allocate about the same amount of RAM as a buffer, so if you only have 4GB of RAM to start with you can run into trouble.  I can't find a reliable source on this one though.


Memory Limit for Windows 

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A portion of usable VRAM will be mapped into the process address space in Direct3D applications, so yes it will count. But you won't end up with the full amount of VRAM being mapped.


This article is a great read in general in regards to memory handling in Windows. Page three gives more information on how VRAM mapping into the process space has changed (included in the spoiler below).




The Growth of VRAM


Another factor in the PC memory equation has been growing as well: video memory size. In the early days of Direct3D, the typical video card had 16 or 32 MB of Video RAM (VRAM). High-end video cards now have 512 MB, 640 MB, 768 MB, or more VRAM. When video cards had 16 or 32 MB of Video RAM, this memory was mapped directly into every process that used Direct3D for efficient access by the application and video driver.


As video cards grew larger, this became unsustainable. A 768 MB hole in the 2-GB virtual address space of each process would leave very little space for applications. Similarly, taking 768 MB out of the 4 GB physical address space would be too constraining. This problem is exacerbated in dual GPU configurations (SLI®/Crossfire™).


Therefore, video card manufacturers typically implement a 256 MB physical memory window for the video graphics memory, and modern drivers do not create direct process mappings for the entire VRAM size. Process address space is still consumed for working with the AGP aperture (64 MB, 128 MB, or more typically on modern game systems 256 MB in size). While PCIe uses a dynamic aperture, it too is mapped into each process that uses Direct3D.


Beyond the direct impact of growing VRAM sizes, more process memory is needed to maintain the backing-store for handling “lost-device†situations so for textures, geometry, and other static data, filling up such large video cards and still fitting under the 2 GB limit is extremely challenging.


The Windows Vista Display Driver Model (WDDM) was designed to address the lost device limitations inherent to the Windows XP Display Model (XPDM), allowing more efficient sharing of the GPU by multiple applications. WDDM does not require the entire 256 MB aperture be mapped in to the process space.


Instead, it dynamically grows the amount as the VRAM allocated by the application increases. For Direct3D 10 applications, this eliminates the need to maintain two copies of resources like textures in memory, one for the VRAM and one in the backing-store for lost-device cases. The system deals with migrating the one copy between memory and the video card, as needed.


Unfortunately, to maintain application compatibility with Direct3D 9 running on Windows XP, two copies of managed resources were still maintained for Direct3D 9 applications running on Windows Vista. This also required process space for maintaining resources like render frame buffers. Previously, render frame buffers were simply lost and recreated. Therefore, they did not require any process space under WDM.


Since the elimination of the 256 MB aperture returned 256 MB of virtual address space to applications on WDDM that was already budgeted for under WDM, this change did not cause any problems until video cards with more than 256 MB of VRAM became available. Small games still had plenty of that 2 GB address space available, but many modern AAA PC titles were running out of space on WDDM.7 The WDDM VA hotfix (KB940105 for Windows Vista, included in Service Pack 1) 8 gives a bit of breathing room by only mapping video resources into the process that need direct CPU access. Games that use Direct3D 10 also have decreased memory pressure without the extra copies required for “device lost†handling.


However, high-end games in development are routinely hitting the 2 GB wall even on Windows XP. In fact, this incident proves that many modern AAA PC titles are already within 256 MB of the 2 GB barrier. Otherwise, they would not have hit this problem until video cards were over 512 MB. 



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So I realize that this thread is almost a year old, but I just rebuilt my computer, and having played Skyrim for two years without too many graphical mods, I figured it would be relatively simple to just add some graphical overhauls to my current mod list and my computer would be able to handle it.


Well, having gone through the installation guides provided by STEP, my computer can in fact run the game in Ultra HD at around 60 fps even through the stress test of the Skyrim Performance Monitor (Everything except the final environment with over 100 actors all trying to fight which I could never get to load).


Similarly, when I have all of my content changing mods installed, the game runs just fine, but if at any point more than something like 1.7 GB of RAM is loaded in one continuous section the game will just hang at the loading screen. (The loading animation will often continue to play but I can see that it has stopped accessing my hard drive through the Performance Monitor, and no more RAM is being loaded).



Provided I load it in small enough chunks I have successfully gotten to 3.5 GB of RAM and 2.1 GB of VRAM loaded at one time at 60 fps, but even with many of my graphical mods disabled I cannot load games outdoors without first loading a game indoors, and with the graphical mods enabled I cannot even enter an outdoor environment at all.



I've been searching for a while for ANY sort of real solution to this problem. Obviously the game is LAA because it can access up to 3.5 GB at a time, and obviously my system can handle the mods... 


System Specs:

Windows 7 x64

Intel i7-3770K @ 3.50 GHz



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There are numerous threads and posts about the 3Gb limit of the application by now.


To sum them all up. Skyrim is a 32bit game and with the LAA update it can now access at the most roughly 4Gb of RAM. However since it is also a DX9 title then most textures are mirrored to some extent in the RAM as well, which puts an effective upper limit to what you can have enabled at any one point.

You might be able to load one set of cells without issue, but once you start traveling then the game just does not clean up well enough after itself for you to run with a large number of memory intensive mods (Texture mods).


So you have to make your mod build so that everything including textures etc etc. can all fit inside a roughly 4Gb space. If you get infinite loading screens then it is because not all assets can be accessed and hence the game just hangs waiting for resources that never come. This is most often due to way too high LOD settings, reduce drawing distances, and or any Z fighting tweaks solves most. But reducing texture sizes is the best solution. Only use 2k textures in exteriors for stuff you really want to look pretty... I personally think armor and skin etc is more vital then rocks and trees, but we are all different in that regard.

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