The link below is an article that absolutely spells it out for system memory, how its interaction with your system and games (FSX..etc) is enacted, and where games are headed...64 Bit.

 

I have read a few documents and articles on this subject, but THIS ONE....can bring anybody up to full speed on why V.A.S. is handled the way it is...and exactly, and truly HOW MUCH is really allocated for FSX and its other 32 bit ilk. It really spells out what we are up against, and WHY...when using FSX, tweaking FSX, and adding a gazillion 3rd party files to enhance it.  Again...I recommend this as an FSX user 'must read'!  The article has 6 pages, and I hope you don't gloss over any of them! The best printed and informative article ever.

 

http://www.gamasutra.com/view/feature/3602/sponsored_feature_ram_vram_and_.php

_{This is a great articel but I would have liked to see the following discussed at the same level of expertise.}

_{How much VAS a 64-bit OS can allocate to itself even when running 32-bit apps with LAE set.  The theoretical limit is 8 terabytes (the other 8TB of VAS would be allocated to a 64-bit app such as X-Plane ver 10.2)  (As we know in a 32-bit OS 2GB of VAS is allocated to the system/kernel and 2GB to the 32--bit app (minus the allocated VRAM)}

_{What happens to VRAM in a 64-bit OS wrt to the 32-bit app VAS (there is still a slight hit) - not much but its still there}

_{How do the various VAS's interact say when you are running FSX, plus a weather engine with its own .exe file and therefore its own VAS and any other add-on that has an exe file and therefore its own VAS and these will need to interact at some level with the FSX VAS.}

_{The importance of VAS fragmentation and the availability of contiguous blocks when the game is running}

_{The use of the term 'virtual memory' for the VAS when Microsoft allocated the term also to the "paging file" - very confusing.}

_{That the VAS is part of the OS - and the Physical RAM is part of the hardware and the VAS only communicates with the RAM via the OS and cpu.}

 

_{Having said that it is an excellent article}

 

_pH

It's a good article but is also 5 years old, it mentions things like the system taking part of the 4gb address space, but that is only relevant to 32-bit versions of windows.  

 

I am still interested in the interaction between the GFX mem and the VAS 4gb. 

It's a good article but is also 5 years old, it mentions things like the system taking part of the 4gb address space, but that is only relevant to 32-bit versions of windows.  

 

I am still interested in the interaction between the GFX mem and the VAS 4gb. 

Here's another one specifically  for 64 bit gaming and systems....

 

http://m.tomshardware.com/reviews/64-bit-vista-gaming,2250.html