As I usually fly short/medium haul flights (FS9) I don't often get OoM CTDs - apart from occasional ones caused by faulty scenery/landclass, which I can usually fix myself.However, if I try flying long-haul (Dublin to Atlanta today), with an a/c which uses up a lot of system resources (PMDG for instance - beautiful as they are) I can get two or three OoM errors before I arrive at my destination.I have FS9 on a pretty good machine, with 2GBs of RAM. (I also have FSX but never use it - much prefer FS9 with all my addons). If I change my OS from XP to Windows 7 64-bit, but keeping the same RAM (which has always tested out just fine with MemTest etc. - I don't think XP/FS9 would use more in any case. No?) am I going to be able to fly long-haul without the OoMs? Maybe someone did the same thing and got a result?Thanks for advice on this - I don't want to spend £££/$$$ and find no improvement in practice (I've read quite a bit re. the theory, but the proof of the pudding, and all that!)!MartinPS. Searched here for: "Windows 7" memory 64-bit - returned no results (???!)

Unless you apply the proper tweak, FS9 will not use any more memory than MS designed it for no matter what operating system is used. There are several posts here at avsim on that topic and the /3GB switch. NickN has a good runthrough over at his usual forum.Here is a good place to start: http://forum.avsim.net/topic/293216-dreaded-out-of-memory-error-in-fs9/page__p__1812190__hl__3gb+switch__fromsearch__1#entry1812190Jim Harnes

I don't think just swapping OS will have any impact on your OOM issues. It might be a little snappier overall, but that might be more a fresh OS vs one in service for a while differences.To get away from OOM errors I think you need to modify FS9 exe so that Windows sees it as "large address space aware" , meaning the OS can safely allocate more than 2Gb of process address space to fs9.exe (if it requests it).There's some difference in the OSs between how they handle pre-fetch of program files, how RAM that isn't allocated to running programs is used, etc that probably has some effect on overall performance. There's also the difference of graphics driver operation (WDDM 1.1 in win 7) which might have an impact on FS9 runs.scott s..

As I usually fly short/medium haul flights (FS9) I don't often get OoM CTDs - apart from occasional ones caused by faulty scenery/landclass, which I can usually fix myself.However, if I try flying long-haul (Dublin to Atlanta today), with an a/c which uses up a lot of system resources (PMDG for instance - beautiful as they are) I can get two or three OoM errors before I arrive at my destination.I have FS9 on a pretty good machine, with 2GBs of RAM. (I also have FSX but never use it - much prefer FS9 with all my addons). If I change my OS from XP to Windows 7 64-bit, but keeping the same RAM (which has always tested out just fine with MemTest etc. - I don't think XP/FS9 would use more in any case. No?) am I going to be able to fly long-haul without the OoMs? Maybe someone did the same thing and got a result?Thanks for advice on this - I don't want to spend £££/$$$ and find no improvement in practice (I've read quite a bit re. the theory, but the proof of the pudding, and all that!)!MartinPS. Searched here for: "Windows 7" memory 64-bit - returned no results (???!)

The earlier responses are correct - in order to use the enhancements that Win7 will provide (and not have to use the /3GB switch entry in your boot.ini file as you must for XP) you must patch FS to use the 'LargeAddressAware' bit in the executable. It does work - I have run the LevelD 767, PMDG 737 and 747 for more than six hours without OOMs while using UT, GE, and pretty much all of the high detail add-on airports with no issues that way. As a side note, Win7 is much happier with 3 - 6GB of physical memory; however, the OOM in FS is not caused by a lack of physical or virtual memory, as many threads here will attest.DJ

The earlier responses are correct - in order to use the enhancements that Win7 will provide (and not have to use the /3GB switch entry in your boot.ini file as you must for XP) you must patch FS to use the 'LargeAddressAware' bit in the executable. It does work - I have run the LevelD 767, PMDG 737 and 747 for more than six hours without OOMs while using UT, GE, and pretty much all of the high detail add-on airports with no issues that way. As a side note, Win7 is much happier with 3 - 6GB of physical memory; however, the OOM in FS is not caused by a lack of physical or virtual memory, as many threads here will attest.DJ

How do you patch it???P.S Never mind, I just found it and applied it. Thanks I didnt know about this.

Hi,Have you tried to right-click on the lower menu-bar, and call up the "Task Manager"? Then you can check how much memory actually is in action.I could imagine that you with an PMDG aircraft come pretty close to your current the upper limit of 2 GB.On my rig with Windows 7/64, REX FS2004 and GE Pro 2, 2 GB is easily exceeded. And I am only running Freeware aircraft, that not are too heavy with regard to RAM.Secondly, I would swap these Graphics cards with a single card such as ATI HD5770 or HD5850.BR,Anders

Thanks for the replies. I have spent many happy an hour here discussing the /3GB switch in the past (I should have said - sorry!) and written a long post on how to fix OoM errors myself (it was here, but my post has been reduced to one odd line - not sure what happened:http://forum.avsim.net/topic/235923-dealing-with-out-of-memory-errors/page__p__1503244__hl__martinlest2__fromsearch__1#entry1503244 ) - but as I said, that really only applies when I know that it is a bgl issue. A long flight across the Pacific/Atlantic is another ball game - nothing to fix from a file point of view.I found that applying the /3GB switch, with the tweaked fs9.exe file, no matter what variation I gave to the figures afterwards, caused my ground textures to go blurred - I never resolved this after hours of tweaking so gave up.DJ, when you say 'you must patch' FS9, you mean use the patched fs9.exe file (and not use the /3GB switch with Windows 7)? Yes, I am not sure increasing my physical RAM would help, I agree. (I'd have to throw out what I already have as I only have two slots for RAM!) - you are right that the OoMs are not caused by a lack of physical or virtual memory (it's an address space issue as far as I can make out). Thanks again,MartinAnders,Yes, I have been checking that.. if I fly freeware a/c I rarely get a problem - PMDG a/c are another matter. I love them, but they use up resources in a way PSS and so on do not (I can get across the Atlantic with PSS's beautiful Concorde, no worries). I thought that I should only use Posky etc. a/c for long-haul, but then I don't get to fly my PMDG heavies of course!!Martin

Thanks for the replies. I have spent many happy an hour here discussing the /3GB switch in the past (I should have said - sorry!) and written a long post on how to fix OoM errors myself (it was here, but my post has been reduced to one odd line - not sure what happened:http://forum.avsim.net/topic/235923-dealing-with-out-of-memory-errors/page__p__1503244__hl__martinlest2__fromsearch__1#entry1503244 ) - but as I said, that really only applies when I know that it is a bgl issue. A long flight across the Pacific/Atlantic is another ball game - nothing to fix from a file point of view.I found that applying the /3GB switch, with the tweaked fs9.exe file, no matter what variation I gave to the figures afterwards, caused my ground textures to go blurred - I never resolved this after hours of tweaking so gave up.DJ, when you say 'you must patch' FS9, you mean use the patched fs9.exe file (and not use the /3GB switch with Windows 7)? Yes, I am not sure increasing my physical RAM would help, I agree. (I'd have to throw out what I already have as I only have two slots for RAM!) - you are right that the OoMs are not caused by a lack of physical or virtual memory (it's an address space issue as far as I can make out). Thanks again,MartinAnders,Yes, I have been checking that.. if I fly freeware a/c I rarely get a problem - PMDG a/c are another matter. I love them, but they use up resources in a way PSS and so on do not (I can get across the Atlantic with PSS's beautiful Concorde, no worries). I thought that I should only use Posky etc. a/c for long-haul, but then I don't get to fly my PMDG heavies of course!!Martin

Martin - correct; you must use the patched FS9 file, but Win7 x64 has no /3GB parameter in boot.ini. Large address aware 32 bit programs are automatically allocated the additional 'memory'. A bonus is that the driver model for Win7 doesn't park the video ram in the same address space as the program so that you can get all of the extra memory for the program.DJ

Mearely my opinion and observation.....Since switching to a 64bit OS and adding the LAA flag to the FS9.exe I have not had one single OOM error. Running Ultimate Terrain, REX, GE PRO, PMDG, FSDT, FlyTampa and so on and so on. Everything is in my sim including the kitchen sink. Repaints, every WOAI package and so on.Not one OOM error (knock on wood) on either W7 64bit or Vista 64bit.A 64bit OS was the best add-on I purchased for FS9.....

Mearely my opinion and observation.....Since switching to a 64bit OS and adding the LAA flag to the FS9.exe I have not had one single OOM error. Running Ultimate Terrain, REX, GE PRO, PMDG, FSDT, FlyTampa and so on and so on. Everything is in my sim including the kitchen sink. Repaints, every WOAI package and so on.Not one OOM error (knock on wood) on either W7 64bit or Vista 64bit.A 64bit OS was the best add-on I purchased for FS9.....

Ditto!Bob ScottColonel, USAF (ret)ATP IMEL Gulfstream II-III-IV-VColorado Springs, CO

Clearly the way to go is Win7-64 - possibly on a new system (though the Dell/Alienware 'ideal' I priced online was well over £4000, so I will have to think again!!). Getting 2 x $GB sticks of RAM for my current setup is £255 instead of the £65 for 2 x 2GBs, so that's not too attractive either..Thank you for replying.Martin"2 x $GB" ... 2 x 4GBs !

Mearely my opinion and observation.....Since switching to a 64bit OS and adding the LAA flag to the FS9.exe I have not had one single OOM error. Running Ultimate Terrain, REX, GE PRO, PMDG, FSDT, FlyTampa and so on and so on. Everything is in my sim including the kitchen sink. Repaints, every WOAI package and so on.Not one OOM error (knock on wood) on either W7 64bit or Vista 64bit.A 64bit OS was the best add-on I purchased for FS9.....

Ditto Ditto Ditto