I recently upgraded my system from 3GB to 4GB. When I do a check of my memory using My Computer Properties I see 3.2GB. If I reboot and do F1 to go to Setup my hardware see's 4GB. I was told by the company support line where I bought the memory that the Windows 32bit OS only recognizes up to 3GB. They gave me the option to send the other 1GB back. But before I do I'm looking for some input from here because I primarily use my system for FS. Any advantage to keeping the 4GB?Thanks in advance to all who reply.Bill

read this this web site and it might help you understand!http://www.hardforum.com/showthread.php?t=1035670

YukonPete,Thanks for the information. Not being very technical I still don't know if I should send the 1GB back.I noticed you have 4GB with Vista OS. Is that 32bit Vista?If I have to tweek my memory allocation to take advatage of the additional memory, well I'm afraid to attemp that. But if leaving it as is, is benificial then I might consider keeping it.Are you saying that there is an performance advantage to keeping the 1GB?Thank You.Bill

and...http://support.microsoft.com/default.aspx?...kb;en-us;294418Regards,

Don't send it back. It will be useful when you convert to Vista. But it will do you no good for Windows XP.Allcott

Basically, unless you upgrade to a 64 bit OS (and I think at least at this point I'd shy away from Vista 64), you will not be able to use more than 3.2. 3Gb is a very generous amount of memory, at least for most software today... so that make the extra 200Mb you are gaining even less beneficial.I can't really see how the memory would be beneficial in your case.

Vista 32bit will have the same issue, will it not?If and when he were to upgrade to a 64 bit OS, he could repurchase the memory then (for a cheaper price, no doubt) and could purchase even more memory since Vista 64 won't have the 4GB barrier. But for now, given the state of drivers and such, he's bound to lose more performance moving to Vista than he gains from adding more than 3GB of memory. Unless he's using some very specialized software, > 3GB is not going to gain you much.

If you look at the last paragraph of the link I posted above (quote below)it clearly states that if you use a 32-bit prg on the 64-bit system, the system will behave as if it were still a 4-gig memory base, BUT it will NOT support the /3GB switch. That means that you will gain nothing by moving to a 64-bit system, XP, Vista or otherwise. You will STILL only be able to access 2gig.< System PTEsA pool of system Page Table Entries (PTEs) that is used to map system pages such as I/O space, Kernel stacks, and memory descriptor lists. 64-bit programs use a 16-terabyte tuning model (8 terabytes User and 8 terabytes Kernel). 32-bit programs still use the 4-GB tuning model (2 GB User and 2 GB Kernel). This means that 32-bit processes that run on 64-bit versions of Windows run in a 4-GB tuning model (2 GB User and 2GB Kernel). 64-bit versions of Windows do not support the use of the /3GB switch in the boot options. Theoretically, a 64-bit pointer could address up to 16 exabytes. 64-bit versions of Windows have currently implemented up to 16 terabytes of address space.>

>If you look at the last paragraph of the link I posted above> (quote below)it clearly states that if you use a 32-bit prg on>the 64-bit system, the system will behave as if it were still>a 4-gig memory base, BUT it will NOT support the /3GB switch.>That means that you will gain nothing by moving to a 64-bit>system, XP, Vista or otherwise. You will STILL only be able>to access 2gig.A couple of points:First, I only just skimmed that, but I believe that's refering only to the memory space as the application in question sees it. I'm pretty sure its not caping all memory being used on the system at 2GB. So you could have App 1 using 2GB, App 2 using 2GB and Vista using 500MB for a total of 4.5 GB.Second, while skimming the net for real-world instances of this problem, I found a page apparently contradicting this limit:A: As a 32-bit application, ArchiCAD can use a maximum of 4GB of RAM. However, some operating systems put a limit on this: Windows XP 32-bit and Vista 32-bit imposes a limit of 2GB. On Windows XP 64-bit edition;Windows Vista 64-bit edition and on Mac OS X, ArchiCAD can use 4GB.http://www.archicadwiki.com/64-bitSo is M$ wrong or is ArchiCAD wrong?

IMHO Microsoft is the source of MS information/data. If you'll go to their site you will see a list of their operating systems. In that list you will find that Windows XP's physical memory limit is 4Gb.http://msdn2.microsoft.com/en-us/library/aa366778.aspxNote: This is a confusing article - the top part says that 32-bit Windows XP can only address 2Gb unless using IMAGE_FILE_LARGE_ADDRESS_AWARE and /3GB in which case it's 3Gb.Then you scroll down towards the bottom and you'll see that the physical memory limit is 4GB. Go figure.fb

I don't expect they are absolutely, definitely wrong - but I would believe they are assuming that you have more than 4 gig of ram in the machine when they say this: mapped kernel memory is not dynamic - it is held in a protected area, and if the whole 4 gig of ram is dedicated to the one app - in this case ArchiCAD - then where does the OS put it's files? Their statement "XP x64 does not have this limit anymore, so it lets 32-bit applications - like ArchiCAD 9 - address the full 4 Gb." appears to directly contradict Microsoft's TID, and I would prefer to believe MS!Anyway - I have left the question with them, and will look forward to an answer. (unless someone else here can tell us).Regards: good subject.

FYI, I found this series of articles on the 3GB switch which does a pretty good job explaining exactly how these address space limits work:http://msexchangeteam.com/archive/2004/08/20/217772.aspxThe jist of it is that an application is given 2GB of address space per instance (though you could have multiple apps running each using up to 2GB). However, applications are not actually limited to allocating memory from within this space-- there are coding techniques to work around this limit. If we assume most of the applications out there that often make use of > 2GB use these techniques, then the 2GB limit shouldn't be much of an issue in practice.

Even with a physical limit of 4GB, that doesn't mean 4GB of memory will actually be availble. Many parts of the system use part of that 4GB allocation space for I/O mapping preventing actual physical memory from being able to use it. A good FAQ to read on the 4GB limit and the actual 3.5GB usable limit is at http://www.hardforum.com/showthread.php?t=1035670While you are there, be sure to check out the Memory FAQ at http://www.hardforum.com/showthread.php?t=760374. It explains all about memory, why it's usually better to use 2 slots than 3, the different kinds, etc.

32Bit Vista can see a total of 4GB but that includes your Video card and any other hardware your running that has memory. So My vista only shows up with 3GB.

Maximum addressable limit for 32 bit OS = 4G Maximum "default" application limit in XP = 2Gbyte = user-mode process space : space 1 application has available. 2Gbyte is reserved of OS and graphics addressable spaceThis space can be in real or paged memory, so even if you have 4Gof physical memory you will get OOM errors in FS9/FSX as thesehave been written for 32 bit computers. FS can only ever get 2G or real/paged memory regardless of the amount of physical memory you have.You can put the /3GB /USERVA=3030 switches in boot.ini that allows anapplication (if appropriately compiled - and FS9 is) to use upto 3G of memory and this does solve FS9 OOM errors, and probablyFSX OOM errors. There are buts to this....1) Some install problems for some programs, (mostly oracle server issues here), but also McAfeee.2) You reduce the available addressable space for the graphics memoryand you can get odd graphics effects.3) You edit your boot.ini file at your peril : you can easily renderyour machine unbootable.4) It is for windows XP PROFESSIONAL with SP1 installed - don't know about Vista.5) have I done this to my home computer - no.http://www.microsoft.com/whdc/system/platf...PAE/PAEmem.mspx