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FSX RAM Usage


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Not a help topic, but just an interesting find I want to report.

I always hear people saying, "FSX does not use a lot of RAM, you only need 4GB." Well I have 8GB on my system, and just a while ago, I was in the FSX aircraft menu, and I got a message: Your computer has run out of available memory. Please restart FSX with different settings..." The task manager showed a total of about 5.5GB in use, with FSX consuming more than half of that - about 3.5GB. No other programs running, and minimal background stuff.

What are your thoughts on this?

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Well, let me start with my opinion.

I think the 4GB think is a bit old. Now that we have tons of high quality addons with better weather and AI traffic, as well as high levels of anti aliasing and filtering and stuff like ENB, FSX is using a lot more memory. Especially now that our CPU's and GPU's can keep up and really unlock the potential of the sim (with, of course, a few tweaks to some .cfg's), I think this is going to be noticed more often.

What was I thinking when I contemplated using only 4GB of RAM when building my computer? :huh:

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Hi. The important thing to understand is that FSX is a 32 bit program and can only use a max of 4GB ram. Task Manager doesn't give an accurate picture of useage.

It is helpful to have >4GB ram as your OS uses some and so do any program's in the background.

Aircraft and scenery get more complex, use up more memory. But the limit is still 4GB until a 64bit flight simulator is released.

Until then you have to drop your slider settings, even if your CPU and GPU can give you good framerates on high settings. The limitation of a 32bit program is what's stopping us getting the full potential out of our systems.

Chris

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Hello,

Frequently, I also get OOM crashes, always in demanding sceneries, and with the PMDG737NGX. I have 16GB RAM. That's why I always thought, that OOM crashes were caused by too less Video memory. I hope, someone could clarify this more.

Henk

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Automation dll errors often occur when you try and access the FSX menu. Some have suggested a fix when using Win7 IIRC. Personally, I've always found the issue when being too eager to access the menu; take it slow yields better results.

Also, referring to a previous post. Don't confuse system RAM and video RAM. Totally different. Often, with the OS video RAM is shared with the system RAM. This can apparently have an impact. But not that I've seen.

Chris

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Hello,

This thread was opened by John. He wrote: "Well I have 8GB on my system, and just a while ago, I was in the FSX aircraft menu, and I got a message: Your computer has run out of available memory. Please restart FSX with different settings..." .

The 8 GB he refers to, is system RAM. The message: Your computer has run out of available memory means an O(ut) O(f) M(emory) crash to desktop. I always thought, that this message had nothing to do with system RAM, but with Video-RAM.

Am I correct, or not???. Please can someone this clarify, perhaps Chris?

Thanks for help.

Henk

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  • Aerosoft

I don't think so Henk.

The error really indicates that the system ran out of memory. Now panica does not state if he is using a 64 bit Os but assuming he does the OS has 8 Gb of memory to use. But FSX being a 32 bit application can only use the first 3,4 Gb (more or less). I have never seen FSX take 3.5 Gb, it almost surely indicates something something is not right. Something is leaking memory.

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This is not new, nor is the solution.

Assuming SP2 or Acceleration, add under the FSX .cfg header

[GRAPHICS]

this line

HIGHMEMFIX=1

It doesn't matter where you put it under that section heading

After, or before, do a Google search on the line and you can read a myriad of topics on the subject, some of which are even accurate... :glare_s:

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Sorry, haven't replied in a while...

I do believe this was related to system RAM, as I rarely max out the VRAM on my GTX 580. Mathijs, I have Windows 7 64-bit (see sig), so yes, my computer does have access to all 8GB. But what is your theory about leaking memory? I thought it was just because of high settings. Oh, and I do have HIGHMEMFIX=1 in the fsx.cfg.

However, this OOM error is a rare occurrence for me. In fact, this was the first time a had gotten it in several months. More often, I experience CTDs and the like, but those are just because of high settings, so they are livable (but I'm currently experimenting with the uiautomationcore.dll to see if that helps).

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  • 2 weeks later...

I don't think so Henk.

The error really indicates that the system ran out of memory. Now panica does not state if he is using a 64 bit Os but assuming he does the OS has 8 Gb of memory to use. But FSX being a 32 bit application can only use the first 3,4 Gb (more or less). I have never seen FSX take 3.5 Gb, it almost surely indicates something something is not right. Something is leaking memory.

Matthijs,

Thanks for making this OOM problem clear to me.

I know about the problem of FSX, being a 32bit program, and the maximum of about 3.5GB usage of FSX. I installed 16 GB RAM, and don't use memory consuming programs like CAD programs or so. Somewhere I read a post, that (too) much memory installed, could be a disadvantage, especially in the case of overclocking the computer. I overclocked my computer (i7-920 processor) at 3.8GHz. Could I better remove 8GB RAM out of my computer?

Thanks for help.

Henk

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FSX, when run on a 64bit system, can address a maximum of 4GB memory (->Virtual Adress Space). However, it uses part of that adress space to access the graphics card's memory. So you must subtract the amount of VRAM that your graphics card has from these 4GB. This applies to DirectX9. I don't know if the DX10 preview in FSX accesses the GPU's VRAM differently.

(Details here: http://forum.avsim.n...5)

So if you have a GPU with 3GB VRAM then that leaves only 1GB of address space for the actual FSX application. You can force FSX to limit the amount of address space used for VRAM access by adding the VideoMemoryOverride option in fsx.cfg

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Thanks Tom,

I have a GTX570 with 1.2GB in my computer. Besides, that I installed a second GPU for a second monitor and the CDUII of VRI. If I must add the VRAM of both cards together, I understand, that could be the problem.

Anyway, I will try out the VideoMemoryOverrdide option, and report back

Thanks again,

Henk

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  • Aerosoft

Matthijs,

Thanks for making this OOM problem clear to me.

I know about the problem of FSX, being a 32bit program, and the maximum of about 3.5GB usage of FSX. I installed 16 GB RAM, and don't use memory consuming programs like CAD programs or so. Somewhere I read a post, that (too) much memory installed, could be a disadvantage, especially in the case of overclocking the computer. I overclocked my computer (i7-920 processor) at 3.8GHz. Could I better remove 8GB RAM out of my computer?

Thanks for help.

Henk

No way, that's all valid for very early Windows XP but MS solved those issues. Insert as much mem as you got, Windows Vista and Windows 7 will make some use of it for sure.

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FSX, when run on a 64bit system, can address a maximum of 4GB memory (->Virtual Adress Space). However, it uses part of that adress space to access the graphics card's memory. So you must subtract the amount of VRAM that your graphics card has from these 4GB. This applies to DirectX9. I don't know if the DX10 preview in FSX accesses the GPU's VRAM differently.

(Details here: http://forum.avsim.n...5)

So if you have a GPU with 3GB VRAM then that leaves only 1GB of address space for the actual FSX application. You can force FSX to limit the amount of address space used for VRAM access by adding the VideoMemoryOverride option in fsx.cfg

can this be true? I see folks with 2 680gtx in sli, so 6GO of VRAM, according to you FSX should not even launch, and it seems to work. strange isnt it? etienne

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You are confusing RAM with address space and Video RAM.

OOM has nothing to do with the amount of available system RAM

OOM has nothing to do with the amount of available video RAM

Address space has little to do with the amount of RAM but everything to do with the OOM

OOM is caused by address space saturation.

That is the answer. A true answer.

How you fix it is by learning the differences as above, and applying the fixes that suit the actual failure, based on your system setup. All of which have been around the FSX community for several years.

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can this be true? I see folks with 2 680gtx in sli, so 6GO of VRAM, according to you FSX should not even launch, and it seems to work. strange isnt it? etienne

I'm not too familiar with SLI, but as I understand it the two cards can be configured in the NVIDIA control panel to act as one single card:

http://blogs.msdn.com/b/ptaylor/archive/2007/03/03/fsx-more-on-sli-and-multi-core.aspx

It would be interesting to hear from these folks with their 2x680gtx setups how they have actually configured FSX, their GPUs and whether they use DX10.

But like I said above: it is mainly a DX9 issue. I do not know whether the DX10 preview in FSX actually removes that limitation. However, that should be easy to find out.

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Just a quick update:

I just ran a test to see if virtual address space for the entire GPU VRAM is reserved during the start of FSX. Turns out it is not. I'm conducting a few more tests to see how far VideoMemoryOverride affects VAS usage. Will report back.

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OK, so I ran quite a few tests this week to find out the effects of VideoMemoryOverride as well as DX10 preview on FSX's VAS usage.

Conclusions:

1. Use of the DX10 preview significantly lowers VAS usage. (In my tests VAS was around 400MB lower and never hit any critical limits as as opposed to DX9).

2. I was not able to notice any effects of the VideoMemoryOverride option on my system (I'm not saying that it doesn't work at all). I have a GPU with 1GB of VRAM. I tried to use different values to force VRAM usage of 0.25, 0.5, 1.0 and 3GB but there was no effect at all. Not on VAS usage, not on VRAM usage.

Maybe VideoMemoryOverride doesn't work for me because my actual VRAM usage is around 900MB and FSX might be able to recognize that. However I would be interested if anyone who has a GPU with >=1.5 GB VRAM can actually get this option to work.

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  • 2 weeks later...

You are confusing RAM with address space and Video RAM.

OOM has nothing to do with the amount of available system RAM

OOM has nothing to do with the amount of available video RAM

Address space has little to do with the amount of RAM but everything to do with the OOM

OOM is caused by address space saturation.

That is the answer. A true answer.

How you fix it is by learning the differences as above, and applying the fixes that suit the actual failure, based on your system setup. All of which have been around the FSX community for several years.

OK, I understand that it's all about the VAS. However, I still have a question. These OOM problem and sometimes an APPHANG CTD, only happens to me when approaching Amsterdam Schiphol (Aerosoft). I have UTX-Europe installed and also NL-2000 v4. I realize, that this scenery is very "hungry". I now have a CPU I7-920 oc'd at 3.8GHz. Should an CPU update, let's say to a I7-2600 or even a I7-3930 make a difference i.e. give me no OOM's anymore, or does a faster CPU have it nothing to do with the OOM problem?

BTW: If I temporary de-activate the photographic NL-2000 scenery of Zeeland, Zuid-Holland and Noord-Holland, I don't get these OOM's.

Woul be glad with an answer. Thanks already.

Henk

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Henk. No, a faster CPU will not address the issues. You say you understand it's all about the VAS, but clearly not as unfortunately the CPU would not address this.

Simply put, with a 32bit program like FSX you'll have a maximum of around 4GB VAS. You can't make it any more.

FSX, your addon plans, your photoscenery, clouds etc. will all eat into this 4GB VAS limit. Once it gets consumed you get an OOM.

So, as you've found removing the photoscenery prevents the OOM as you are staying with the VAS limit.

With today's heavy addons you sometimes have to compromise. Reducing your slider settings can also help.

Chris

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  • Aerosoft

Thanks Chris, for your answer. To be quite honest, I already was afraid, that it wouldn't help.

Kind regards,

Henk

But keep in mind that as long as you use a 64 bit OS the OS itself and all the other up to date software you use will not be limited to the lower 3.7 Gb. I got 16 Gb and I run the full MS Office suite (64 bit version) and Adobe Photo Shop while running FSX and it will not cost me one FPS. Okay every 5 minute Outlook gets mail and that might drop fps by 1 or 2.

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But keep in mind that as long as you use a 64 bit OS the OS itself and all the other up to date software you use will not be limited to the lower 3.7 Gb. I got 16 Gb and I run the full MS Office suite (64 bit version) and Adobe Photo Shop while running FSX and it will not cost me one FPS. Okay every 5 minute Outlook gets mail and that might drop fps by 1 or 2.

Thanks Matthijs. I also noticed, that I can run programs like ASE (realtime weather) and other FSX add-ons, without loosing framerates. As a matter of fact, there is (still) no need to update my CPU, because, I'm quite happy with my frame-rates now.

Thanks again to all for helping me out.

Henk

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  • 2 months later...

But keep in mind that as long as you use a 64 bit OS the OS itself and all the other up to date software you use will not be limited to the lower 3.7 Gb. I got 16 Gb and I run the full MS Office suite (64 bit version) and Adobe Photo Shop while running FSX and it will not cost me one FPS. Okay every 5 minute Outlook gets mail and that might drop fps by 1 or 2.

But keep in mind that as long as you use a 64 bit OS the OS itself and all the other up to date software you use will not be limited to the lower 3.7 Gb. I got 16 Gb and I run the full MS Office suite (64 bit version) and Adobe Photo Shop while running FSX and it will not cost me one FPS. Okay every 5 minute Outlook gets mail and that might drop fps by 1 or 2.

Mathijs - what is the verdict on the use of memory? I recently overclocked my computer and had been told to remove 8gb of memory from the original 16gb. I found it odd to hear that too much memory hurts performance and that too much memory can overheat your computer. It is hard to accept a philosophy on this topic because there are countless opinions on the subject. Anyhow, I came across the 8gb of memory that I had removed a while back and decided to stick it back in the PC. After all, they cost a lot of money and I am not going to let them go to waste. Performance has been unchanged but I will be watching the temperature of the CPU. Welcome your opinion.

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