For those of you using 32-bit Windows you might want to seriously consider using 64-bit windows. Why? If you have 4gb of system memory and 1 gig of memory on the video card (Example: GTX460) Windows has to map that 1 gig of memory so now your down to 3 gig of system memory. Windows Home premium needs 1 Gigabyte of memory to run optimially. So now your left with 2 Gig of system memory for FSX and any other flightsim addons you happen to be running. The PMDG planes have always been very complex and demanding of system resources as you already know. 2 gigabytes just doesn't cut it. So its possible your starving your Sim of memory it needs to run optimally and after awhile it can't cope with the load your putting on it and then you get an OOM or CTD. 64-bit windows doesn't have the memory mapping issue so if you had 4 gig of ram and 64-bit windows it would use all 4 gig of the memory so at the very least you would have 3 gig of memory available to FSX (After Windows OS gets what it needs) then cause that 1 gig video card is not being mapped. Even though FSX is a 32-bit program and can only use a total of 4 gig of system memory, your other programs need memory too including windows. So you can see the benefit of running a 64-bit operating system and more memory. I have 8 gig of system memory and it works very well for me. PMDG also highly recommends 64-bit for their planes for good reason. It isnt cause they are in the cahoots with Intel and want you to spend more money. It is what it is. Shrug. If you read the reviews for the MD-11X and 747-400X all of them state that they were able to run the sim more smoothly with 6 to 8 gig of memory and that anything less caused OOMs and CTDs. I don't see the 737-NGX review being any different when it comes out considering the NGX is the most complex plane released yet. I had the same problems when I had 32-bit Vista with 4 gig of ram. so I sent Microsoft 10 bucks and they sent me the 64-bit version that works with my 32-bit Key. Upgraded to 8 gig of system memory and no more OOMs and everything runs very smoothly. Yes there are some issues with the NGX that need to be worked out. However the reason some of you are having so many issues, and others are running flawlessly could simply be because your putting too much demand on your system and don't have the resources available to cope with it.

Paul, It is not correct at 100%, I had some OOMs earlier this month despite having 8GB RAM and Windows 7 64bit.The problem, stated also somewhere here, is the virtual addressing space (aka VAS), not the amout of GB RAM mounted. In a 32bit OS you should, for example, to do the 3GB switch, by increasing the UserVA. In a 64bit OS you don't have to do this but OOMs can happen because FSX is anyway a 32bit application, so it cannot handle more than 3,5-4,0 GB of space, of virtual address space.

Paul, It is not correct at 100%, I had some OOMs earlier this month despite having 8GB RAM and Windows 7 64bit. The problem, stated also somewhere here, is the virtual addressing space (aka VAS), not the amout of GB RAM mounted. In a 32bit OS you should, for example, to do the 3GB switch, by increasing the UserVA. In a 64bit OS you don't have to do this but OOMs can happen because FSX is anyway a 32bit application, so it cannot handle more than 3,5-4,0 GB of space, of virtual address space.

Ok I am not gonna argue if you want to get technical about it. However in the 3 Years I have had 1st the PMDG 747-400X, Then the MD-11X and now the 737-NGX. I have never ever had an 00M error period. Don't tell me its luck either. However I do notice one thing different between the setups for people that having a lot of issues with OOM and those like me that are not. I'm still using a finally tuned Vista 64-bit system and you guys are using Windows 7.But if you ask anyone with any extensive experience with FSX and Complex Planes and add-ons they are all going to recommend using Windows 64-bit.

No Paul, I don't want to say you were lucky. :)Furthermore, I don't know which addons you run. You know, many times OOMs come from a mix of factors:heavy aircraft addons, high detailed terrain mesh, ground and sky textures and so on. Somenone cannot get OOM while using PMDG 747X because don't stress the system with other addons.I just wanted to clear that using a huge amount of RAM does not necessary lead to none OOMs, because these messages are not related to that.Finally, using a 64bit OS and more than 4GB of RAM can reduce drastically the presence of OOMs and for this reason it is suggested to setup this kind of hardware. P.S.: to respond to you last comment. 64bit OSs are recommended because they don't lack about the VAS, which is a lack of 32bit OSs, so with them you can address more space and your next limitation is due to running 32bit applications.

Furthermore, I don't know which addons you run ...

I use the Following add-ons. ASE, GEX, REX, UTA, UTX, UTII, and FS Global 2010. I also have 93 FSX Payware airports from all over the World. (Orbx, FSDreamTeam, FlightBeam, Armi Project, FlyTampa, Aerosoft, UK2000, EireSim, LatinVFR, Imaginesim, TropicalSim and Blueprint. Have 4 Planes, PMDG 737-NGX, MD-11X, 747-400X and the Level-D 767. Still no OOMs with all of the above after switching from 32-bit and 4gb to 64-bit and 8gb. System SpecsQ6600 Quad Core with go stepping. 2.4 ghz stock / Overclocked at 3.15 ghzZalman 9700 CPU cooler8 gig OCZ Reapers 4x28800gtx with 768 meg ram900 Watt OCZ Mod-Extreme Power SupplySaitek X52 Pro Flight Controllers and Rudder PedalsFSX and all Addons on dedicted DriveWindows Vista 64-bit

ok. bye and congrats for all your addons and hardware config.

Did you open a ticket with PMDG support?