Hello Word Not Allowed, interesting post! Clearly, you do know a great deal about this. I'm interested in your comment that I've quoted above. I too am now on W7 64 bit. I assume that deactivating the page file has the advantage of less accessing of the HD by Windows so helping improve performance. Any points to watch out for? Are there any limitations?Iain Smith

Thanks! What do you mean exactly with the "comment you've quoted above"?Deactivating pagefile has, for me, an advantage of not having disc do unnecessary work. If I ever need more RAM, I'll get it, DDR2 is so cheap nowdays, its a disgrace ;-) But for now, my 4GB have never failed me yet.I saw only once, FS going over 3GB (and that was a very bad scenery), so if I had MANY other programs running I could kick the 4GB to its limit, but I said, I usually run a very clean system, have all my secondary flight programs on my laptop, main computer is only for the flight.From my point of view and my tests, if you have enough RAM, 64bit system and modified FS executable, by all means, turn off the pagefile. Just know what you are doing :-)And the limitation in that case is only your physical RAM (working size) - modified FS9.exe will in ANY case still have 4GB limit, instead of 2GB (virtual size). Meaning, even if FS9 reaches 4GB of virtual size, question is how big is working set, depending on that, and other programs running and using physical ram, would you know how much is free of the physical ram. All in all, even if FS9 would reach the 4GB VS, still you would probably have enough headroom on the 4GB system. FS9 would OOM again at 4GB. Call me when you manage that ;-)

Hello Word Not Allowed, interesting post! Clearly, you do know a great deal about this. I'm interested in your comment that I've quoted above. I too am now on W7 64 bit. I assume that deactivating the page file has the advantage of less accessing of the HD by Windows so helping improve performance. Any points to watch out for? Are there any limitations?Iain Smith

As a matter of interest, since I've been using my new i7 'puter with Win7 x 64 and 8GB DDR3, I have yet to write one single byte to my pagefile... :( Also, there still seems to be a bit of confusing with terminology.Virtual Address Space (which is what the whole issue around which the /3GB switch revolves) has absolutely nothing to do with the amount of physical memory, or virtual memory (aka: page file).Every running application has its own, unique VAS Table. It is simply a table of memory addresses that is used whenever the OS has to swap the focus of any application to screen (Alt-Tab). If you have eight programs (applications) running at the same time, the OS will keep track of eight VAS Tables.The size of each application's VAS Table is determined by whether the app has the LARGE_ADDRESS_AWARE flag set in the app's header, and whether the /3GB switch is set, and the size of the configured userva set. By default, all 32bit applications have a maximum size of 2GB VAS. The maximum one may increase the userva setting is 2.5GB. Often that extra 0.5GBs is all that's required to prevent an OOM error from occurring.

As an aside, I flew the PMDG MD-11 into LFPG last night, FS9 maxed, AS weather, RC4, GEPro-ed and Rex-ed with FSBuild in the background and read 3.25GB VM usage in Win 7 x64 (upon landing). Moving to a 64 bit OS was the best thing I ever did (besides updating my PC to something that can run FS9.75 ( :( ) beautifully). Many thanks to some of the links in this thread I got to where I am today, wouldn't have had a chance of getting here otherwise.So a big cheer for all the AVSIM members!BTW, for anyone sitting on the fence when it comes to updating to a 64-bit OS, just do it. You won't regret it, and won't ever look back either. To see FS9.75 running at full steam with no OOM errors is truely a sight to behold. Hard to believe that FS9 is now close to 7 years old.Cheers, SLuggy

As a matter of interest, since I've been using my new i7 'puter with Win7 x 64 and 8GB DDR3, I have yet to write one single byte to my pagefile... :( Also, there still seems to be a bit of confusing with terminology.Virtual Address Space (which is what the whole issue around which the /3GB switch revolves) has absolutely nothing to do with the amount of physical memory, or virtual memory (aka: page file).Every running application has its own, unique VAS Table. It is simply a table of memory addresses that is used whenever the OS has to swap the focus of any application to screen (Alt-Tab). If you have eight programs (applications) running at the same time, the OS will keep track of eight VAS Tables.The size of each application's VAS Table is determined by whether the app has the LARGE_ADDRESS_AWARE flag set in the app's header, and whether the /3GB switch is set, and the size of the configured userva set. By default, all 32bit applications have a maximum size of 2GB VAS. The maximum one may increase the userva setting is 2.5GB. Often that extra 0.5GBs is all that's required to prevent an OOM error from occurring.

Bill, very well put together. I rather tried to give a simplified explanation, as to how to check how much and what FS9 uses. VAS is the exactly what I was talking about, the virtual space. Just as clarification.

Word Not Allowed, how about pagefile with XP 32bit but using the /3 gig switch and the modified exe along with 4 gigs of memory...should pagefile be on or off?

Also OK I think. You are providing 1GB of VAS to the OS (if I interpret this /3GB switch correctly, mind me, I never used it), which is in XP sense more than enough - depending what you are using under XP.

I fixed the problem. I upgrated with window 7 pro 64 bites.Al