Getting 32 bit apps to adress more than 2gb Ram

How do i get my 32 bit apps to adress more than 2 gb of ram? Ive heard you can increase it to 3 or 4 gb & since i have 8gb of ram i dont see any downside to doing so, but ive only heard rumors that this is possible.

In 32 bit Windows operating systems, the total addressable space available is 4GB. So if you install a total of 4GB (or more) worth of RAM, the system will detect/use/display less than 4GB of total memory because of address space allocation for other critical functions, such as:

- System BIOS (including motherboard, add-on cards, etc..)
- Motherboards resources
- Memory mapped I/O
- Configuration for AGP/PCI-Ex/PCI
- Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size. e.g. more PCI cards installed will require more memory resources, resulting of less memory free for other uses. The biggest consumer in this group is obviously the graphics card(s).

This limitation applies to most chipsets & Windows XP/Vista 32-bit version operating systems. Again, this is a limitation of the Operating System not having enough address space to allocate to the system *and* the RAM. Not allocating address space to devices renders them inoperable. Not allocating addresses to RAM simply results in the unaddressed section not being used in an otherwise fully functional computer. Therefore the OS designers assign RAM last. This approach, while not perfect, at least ensures a functional computer.

Therefore:

If you install a Windows operating system, and if more than 3GB memory is required for your system, then the below conditions must be met:

1. A memory controller which supports memory swap functionality is used. The latest chipsets like Intel 975X, 955X, Nvidia NF4 SLI Intel Edition, Nvidia NF4 SLI X16, AMD K8, and newer architectures can support the memory swap function.

2. Installation of Windows XP Pro X64 Ed. (64-bit), Windows Vista 64, or other OS which can provide more than 4GB worth of address space.



Note: Windows Vista 32bit SP1 will display the installed amount of RAM. This is a display change only.

Re read your post - Are you referring to the 3GB switch??

My understanding is that the /3GB switch forces x86-based systems to allocate 3 GB of virtual address space to programs and 1 GB to the kernel and to executive components. Simply: It moves the starting point for system related functions from 2GB to 3GB. Be advised the programs you run need to be designed to address the extra memory, or you will have (in essence) taken 1GB away from the kernel/system for no return.

Use of the /3GB switch in Exchange Server 2003 on a Windows Server 2003-based system


Information on Application Use of 4GT RAM Tuning

fieseler said:

How do i get my 32 bit apps to adress more than 2 gb of ram? Ive heard you can increase it to 3 or 4 gb & since i have 8gb of ram i dont see any downside to doing so, but ive only heard rumors that this is possible.

Click to expand...

By default, 32 bit OS's have a 4GB virtual address space. 2GB of that space is allocated to the app, the other 2GB to the system. Using the /3GB switch in the boot.ini allocates 3GB to the app and 1GB to the system. Even if you do use the /3GB switch, the app will have to be recompiled (if it is not already Large Address Aware) to use that space. PCI configuration requirements reduce the memory available to the operating system (usually between 200MB and 1GB). More if you have an 8800GTX. The 1GB available on some video cards is really 512MB per GPU, so it won't be as big of a hit as an 8800GTX. This switch can cause system slowdown and instability.

Even in a 64 bit OS, all 8GB will be used, but 32 bit apps will still be limited to 2GB.

Hope I was able to make this understandable.

i have 64 bit vista, & 6 gb of ram, 1gb - 1.5gb is used by windows so that leaved 4 gb at least free & my games only use 2gb which is wasting another 2 gb of ram so i want to see if i can get 32 bit apps ie all my games, to use more than 2gb.

fieseler said:

i have 64 bit vista, & 6 gb of ram, 1gb - 1.5gb is used by windows so that leaved 4 gb at least free & my games only use 2gb which is wasting another 2 gb of ram so i want to see if i can get 32 bit apps ie all my games, to use more than 2gb.

Click to expand...

If I may provide a "New York English" translation of the above:

(1) The /3GB switch applies to 32 bit windows. It does not apply to 64 bit versions.

(2) The game you are playing has to be written to USE the 3GB switch. If it is not, then changing a setting in Windows does nothing for the game, and may cause instability.

(3) What having more RAM on a 64 bit system does is allow more things to run and not impede on each other. You cannot force a game that isn't designed to use more than 2GB to do so.


If I may be very very blunt, and if I have a proper understanding of what you want: The answer is "No".