I just want to re-iterate that the process using more than 2G of process address space and the OS using more than x amount of physical RAM are 2 entirely different concepts.32-bit processes can address 4G using a 32-bit address value. In Win-32 this 4G is split into 2G for the app and 2G for the OS. The /3G switch lets the app access more than 2G of process address space, up to the 3G line. I covered this in a blog posting here:http://blogs.msdn.com/ptaylor/archive/2007...ress-space.aspxDepending on your mobo and Northbridge chipset, 32-bit flavors of Windows can access up to 4G. If you cannot get 32-bit Windows to recognize the RAM it is usually BIOS or Chipset or Motherboard or all of the above. The reporting may vary because of how the OS maps various elements into its own space. I covered this in a blog posting here:http://blogs.msdn.com/ptaylor/archive/2008...-is-in-use.aspxI hope that helps clarify what exactly we are talking about.

I can confirm that 4 of the latest DDR3 and DDR2 motherboards that I tested in the last year with the newer chipsets, do in fact have a memory map support in the BIOS/chipset which does address greater than 2GB installed.Also, there are mapping features specifically designed for 64bit OS as well to ensure proper useMemory Remap Feature {ENABLE}Allows you to enable or disable the remapping of the overlapped PCI memory above the total physical memory. Enable this option only when you install 64-bit operating system. Configuration options: {Disabled} {Enabled} DEFAULT:{Disabled}Older motherboard must be confirmed however from what I can see the trend is to make sure the support is there for the newer productsMy point is, many of the support settings in a BIOS for mapping are DISABLED by default and are not AUTO detected. Older board should be confirmed they will in fact address memory above 2GB properly, and, confirm (on any board) the DIMM slots the memory product is installed to are in fact correct for that use.

Ok, now my brain-cloud is acting up. I read the articles and still must ask the question.With WXP(sp2) can I use 4 gig of system memory?I assume this is yes.But will any of this memory be available to FSX?If yes then I assume the FSX performance might be better.Thanks.

>I just want to re-iterate that the process using more than 2G>of process address space and the OS using more than x amount>of physical RAM are 2 entirely different concepts.>>32-bit processes can address 4G using a 32-bit address value.>In Win-32 this 4G is split into 2G for the app and 2G for the>OS. The /3G switch lets the app access more than 2G of process>address space, up to the 3G line. I covered this in a blogYes, this is all good info Phil, I used your blog as well, thx. I got my mobo P5W DH DELUXE understand 4Gb (a switch in BIOS), I use /3GB /userva=2560 in Boot.ini and have my FSX SP1 and FS9.1 modified to handle >2Gb address space (just in case, I had no problems, lol). Now, when I boot in Vista 64 SP1 to run FSX SP2 I don't need to touch anything for 4GB RAM compatibility.One question though, I'm really interested to get the answer to: I got 8800GT videocard with 1Gb onboard. Can it be detrimental to the performance of my system? I understand it may take up some resource from the space also used by the system/OS and come in conflict with each other?Thanks.Dirk.

>Ok, now my brain-cloud is acting up. I read the articles and>still must ask the question.>>With WXP(sp2) can I use 4 gig of system memory?>I assume this is yes.>>But will any of this memory be available to FSX?>If yes then I assume the FSX performance might be better.I doubt so. It was said it could help some OOMem errors only, that I have yet to see on my system. For what it matters I used the 4Gb adaptatiion mainly out of curiosity and also because I have WinXP and Vista installed on 2 of my 3HDDs on the game pc and I don't want to change the switch in BIOS every time I boot into one of them. Always 4GB aware now.

DirkI can not speak for Phil and I have never used your motherboard product however I can relay the following1. If I understand your post correctly, the switch you have placed in the boot.ini file is not needed. You have a 64bit OS and that edit is unnecessary and should not be used. If what you are saying is you are 'dual-booting" and you have that edit on a 32bit OS boot.ini, then it is correct for that use.2. I would need to download and look at your motherboard manual, however, if you have indeed set the BIOS up correctly as you specified, the 1GB memory on the video card is fine, especially within the confines of a 64bit OS. In a 32bit OS that amount of memory does push things a bit however it is still OK at 1GB.

Thanks, Nick. As I wrote I use both: WinXP SP2 with FS9 and FSX SP1, and for learning and smooth upgrade of myself and my system I have started to fly FSX SP2 under Vista 64. On the same pc, different boots.

>In a 32bit OS>that amount of memory does push things a bit however it is>still OK at 1GB.>This part really worries me. How much can it (1GB card) actually push things? I'm very much interested in your comments, guys. I'm not gonna switch completely to Vista now, on the contrary, most of my flightsims are WinXP based, so I don't want 1GB if it is a an obstacle for WinXP 32-bit.

It's in the mapping area of address space Dirk, not the PM... as the video memory increases it must be mapped and that is part of the post Phil made in his blog, about how that worksNo worries, your fine. :)

>>>It's in the mapping area of address space Dirk, not the PM...>as the video memory increases it must be mapped and that is>part of the post Phil made in his blog, about how that works>>No worries, your fine. :)Thanks again, Nick. I'm happy now. :)

on 64-bit Windows, no.on 32-bit Windows, yes the graphics adapter memory can squeeze the space for the OS. that is why I recommend userva=2560 and not 3072, the extra 512 for the OS means less squeeze factor

having more physical memory for the OS means less use of the (slower) page file and swapping between disk pages and actual physical RAM pages.and it isnt just important for FSX, as the OS can be doing other things and having more RAM thus means the OS doesnt have to swap your FSX physical RAM pages out to perform that background service activity.so yes having more than 2G of physical RAM can mean better overall performance.

NickAn interesting little exercise we could try is for people to:Click Start/RunKey in msinfo32Open up the Hardware Resources sectionClick on MemoryMSinfo32 is included in XP and Vista.For instance I have Vista 32 bit, 4Gb physical memory and a xfire x1950 setup. There are 7 instances of Radeon x1950 listed, including one in low memory. For example, one of the instances is allocated to the following address space:xD0000000 - xDFFFFFFFwhich is decimal 3,489,660,928 - 3,758,096,383which is allocated in the 3-4Gb areaIn fact, all of the allocations that I see are in the 3-4Gb space with the exception of a few which are in low memory. The allocations are not contiguous and there are gaps and some allocations appear to be used by various resources. I have no idea why this is but the 'where' and not 'why' is of interest now.What would be interesting is to see what kind of allocations get used in other PC configurations, such as with 2GB physical mem or Vista 64bit with 8Gb etc.Tip: If anyone wants to try this it helps a great deal if you tick the View/Digit Grouping in the Windows calculator to on when you do the conversions.If you click on the header 'Resource' in the msinfo32 detail screen, it will sort the entries by address.

>on 64-bit Windows, no.>>on 32-bit Windows, yes the graphics adapter memory can squeeze>the space for the OS. that is why I recommend userva=2560 and>not 3072, the extra 512 for the OS means less squeeze factorSo, I've got 2560 allocated for the game, 1 Gb goes to my video and the OS is left with less than 500Mb. Is it enough for WinXP 32-bit?? Are 2560 occupied by the game continously or just in splashes?Thanks.

Hi DirkI think you may be mixing up the use of physical memory with "address space" a bit.This is a quote from Phil's blog..."Note this switch needs to be used with care, since PCI-Express maps the entire address space of the graphics card into the OS address space. If you set the app to use 3G with a 768m graphics card, that leaves 256m for the OS. A better setting is 2560, eg 2.5G, since that leaves 768m for the OS with a 786m graphics card. Much more reasonable."So what we are talking about here is the address space reserved for the OS based on the amount of video memory... in your case 1GB is squeezing the address space for the OS even tighter than 768MB, so, to compensate you could LOWER the boot switch value.If you wanted to MATCH the amount of address space allocated to the OS in the suggestion Phil made for that number, and, allow for the incresed VM of your card, your boot switch value would be lowered to 2304. The exact spot that is best is based on several factors however What Phil is saying in his blog about address space is that it is better to let to OS have a bit of breathing room in that value.I would leave it at 2560 and see how it fairs... if you see any OOM problems, LOWER it 128 to 2432 and make sure the value you set the switch to can be divided by 64 evenly.