Recently I encounter some frequent OOM issues with NGX. I checked RAM usage in resource monitor and found that fsx only use 1.5G, while more than 800MB is available. I don't think I ran out of RAM. But could OOM be caused by insufficient video memory?

 

I am using 32bit windows 7 with 4G ram installed.

 

Here are two screenshots captured when I receive OOM error. The second one is made after FSX shut down.

 

Any help is appreciated.

Just to verify one thing. If fsx used all video memory, will OOM message shows up? If yes, I think I need to upgrade my outdated video card.

FSX is most dependent on the CPU. The GPU should not be the cause of an OOM. If you have the 32 bit OS installed, make sure you have deployed the 3GB switch so that FSX can see more than 3GB's. The 3GB switch is discussed at length in the memory section of this guide - http://www.simforums.com/forums/topic29041.html. FSX can only 'see' up to 4GB's but if that's all you have installed, then you probably can't use more than 3GB's as the remainder has to be used for your operating system and other components (including your video card).

 

Best regards,

Jim

FSX is most dependent on the CPU. The GPU should not be the cause of an OOM. If you have the 32 bit OS installed, make sure you have deployed the 3GB switch so that FSX can see more than 3GB's. The 3GB switch is discussed at length in the memory section of this guide - http://www.simforums...topic29041.html. FSX can only 'see' up to 4GB's but if that's all you have installed, then you probably can't use more than 3GB's as the remainder has to be used for your operating system and other components (including your video card).

 

Best regards,

Jim

 

Thanks. I will try and report back.

OOMs are not caused by physical memory (either system RAM or GPU) - what's actually happening is that you're running out of virtual address space for the fsx.exe process. VAS is basically a mapping system for memory anywhere in the system that happens on a per-application basis. No 32-bit application can ever use more than 4GB of it and with DirectX 9 games your video memory usage is included in this limit and actually gets copied by the game, doubling the hit it has on it. Even if you're only using 1.5-2.5GB of physical RAM, the video memory and its copy on top of that can easily make it go over the 4GB barrier and crash.

 

This isn't limited to FSX - other large-world games like Skyrim, Planetside 2 etc have stuggled with the OOM issue as well. The only true solution is a 64-bit executable, which we're unfortunately never going to get for FSX.

OOMs are not caused by physical memory (either system RAM or GPU) - what's actually happening is that you're running out of virtual address space for the fsx.exe process. VAS is basically a mapping system for memory anywhere in the system that happens on a per-application basis. No 32-bit application can ever use more than 4GB of it and with DirectX 9 games your video memory usage is included in this limit and actually gets copied by the game, doubling the hit it has on it. Even if you're only using 1.5-2.5GB of physical RAM, the video memory and its copy on top of that can easily make it go over the 4GB barrier and crash.

 

This isn't limited to FSX - other large-world games like Skyrim, Planetside 2 etc have stuggled with the OOM issue as well. The only true solution is a 64-bit executable, which we're unfortunately never going to get for FSX.

 

Thank you I think this is extremely helpful. You explained why I get OOM. 1.5G RAM usage plus some video memory surely exceed 2G limitation for my 32-bit Windows. I'll upgrade my windows to 64bit because 4GB is pretty enough for me. Hope this problem get solved.

I tried that 3GB switch and tested with all settings maxed out at KLAS. It's working. Thank you Jim.

I thought there was a MS DX9 or OS patch a long-while back that basically limited the footprint GPU VRAM has in the VAS array? I know DX10 does not have any GPU VRAM mapped to the VAS which is why VAS goes down when switching to DX10 mode in FSX. On top of that, I could've sworn some FSX DX9 users tested the specific affects of today's GPU's with large amounts of VRAM and could not make it show any appreciable difference in the amount of VAS consumed as shown ProcExp, including various settings of the VRAM limiter available to the fsx.cfg. In the last years, I've jumped from a GPU with 1, 1.2, 1.5, and 2.0GB of VRAM and the amount of VAS consumed by FSX has not changed significanly. So, my current understaning is that VRAM in DX9 will consume some amount of VAS but it's not a 1:1 ratio and capped at some extent.

"I thought there was a MS DX9 or OS patch a long-while back that basically limited the footprint GPU VRAM has in the VAS array?"

 

I'm scouring the internet for some confirmation to this myself as I need a new video card and I am on the fence trying to decide between buying one with 2 or 4 gb of VRAM. I want to use multi monitors and I suspect the extra VRAM will help. Right now I know just enough about this stuff to get myself in trouble.

 

Ted

For that 3gb fix I didn't see a section for windows 7, is it just the same procedure as vista?

For that 3gb fix I didn't see a section for windows 7, is it just the same procedure as vista?

 

Yes.

 

Best regards,

Jim

I just hit my first OOM error halfway through a flight from KSFB to KABE using the CoolSky MD-80 Super Pro. I was also running FS Commander, Radar Contact and the REX Essentials weather. My computer is a quad core with 4 Gb RAM and the GPU is an EVGA GeForce GTX650 w/1 GB RAM. I'm also running Win 7 64-bit with FSX running in DX10 Preview mode. And running with textures in the 4096 HD mode. Cruising along when I started hearing chimes, and then I ran out of memory.

 

So what would be the first thing(s) I should start eliminating in this menagerie? Trimming w/nVidia Inspector? No FSC? No RC? Adjusting sliders? If it's not physical RAM...

If you have your LOD_Radius= set higher than the max (4.5) in the FSX.cfg, then you need to return it to 4.5.  Anything higher is a known cause of OOM's.  If texture_max_load is set to 4096, it is taking up resources.  REX weather has graphic settings.  If you have those set to 4096 instead of 512 and also have texture_max_load set at 4096, then you are going to create an OOM as no computer running today can operate with those high settings for very long.  It could be just a combination of high settings that are causing your OOM(s), like weather, commercial aircraft, commercial scenery, high fsx settings and high display driver settings.  The FSUIPC4 program has an alert (chimes) that tells you that you are beginning to run out of resources and you need to do something quick to reduce the stain on your computer.   

 

Hope this helps.

 

Best regards,

Jim

 

So, my current understaning is that VRAM in DX9 will consume some amount of VAS but it's not a 1:1 ratio and capped at some extent.

 

Al, that was/is my basic understanding as well, but this only relates to a 64 bit version of Vista and later, and the OP has a 32 bit system. 

 

Some time back, I'd found a MS KB article which talked about this, but I didn't save it.  It was a patch that came in with Vista 64, pre SP1 to deal with the "legacy" DX version memory issues and was subsequently included in later Windows service packs.

 

In my own informal tests looking at DX9 vs DX10 and VAS usage, I actually found that in many cases my FSX in DX10 mode was using slightly more VAS, though my tests were pretty simplistic and didn't cover long flights between complex airports.  Still, others experiences certainly suggest that DX10 can help mitigate OOM issues, so I expect the discrepancies between the two must increase in DX10's favor as time/complexity increases.  I never did further tests, as I've only OOM'ed a couple of times and a few of the outstanding DX10 issues will occur with several of my airports so I've stuck with DX9 for the time being.  If I were getting even semi-regular OOM's I'd sure be looking at this in more detail, though.

 

Scott

Well, my LOD_RADIUS=4.500000, and my TEXTURE_MAX_LOAD=1024 (although I could have sworn it was 4096). REX Essentials has a choice 3D Cloud HD resolution of 4096x4096, 2048x2048, and then 1024x1024 and 512x512, with an add-in of DXT5-optimized clouds. I had the 4096 and DXT5 checked off. REX also states in their manual:

 

If you wish to view high-definition textures within FSX, you must make sure to set this value in the FSX.
cfg file. Add TEXTURE_MAX_LOAD=4096 within the DISPLAY section of the FSX.cfg file.

 

Will changing from DX10 back to DX9 mean anything? I have no add-on airports besides a tiny little FA08 here in Florida, so DX10 isn't a "msut-have" if it means a lesser possibility of OOMs. For now, I'm going to change my TEXTURE_MAX_LOAD=4096, choose 2048 3D cloud resolution in REX, and use FSC only for building the flight plans instead of using the GPS function, which requires me to run it alongside FSX. I can go back to DX9 if it will help, but I'll try the other methods first.