Hi
Ive got new dell 1530 with 4gb memory, and I experience same issues with games test performance - with each game I have installed on my system which has test performance, is always the same problem - it shows only 2048 instead 4096MB of RAM ..

Everything seems to be fine both bios and vista recognizes 4gb of my memory... In game perfermormance tests it physical memory - 2048, page file - 4095Mb..I am so confused..

thanks 4 help

In 32 bit Windows operating systems, the total addressable space available is 4GB. If you install a total of 4GB 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.

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.

We can have long debates about mathematical fundamentals and discussions about why the original Windows designers couldn't allocate the full theoretical max of 36 bits of address space so that users today would be able to use more resource. But at the end of the day, the designers and engineers 'Didn't Then'. So we 'Can't Now'.


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.



ALSO - There is an additional technical limitation associated with 32 bit applications in that the app itself is limited to not use more than 2GB of RAM. There is a /3GB switch that can be enabled in the start up: http://www.microsoft.com/whdc/syst [...] AEmem.mspx

Be advised that enabling the /3GB switch takes away 1GB of memory space from the Operating System (from 2 to 1) to give it to application space - Read: "No Free Lunch" If your OS runs out of address space, it could get a little ugly...


The /3GB switch does not apply to 64 bit operating systems.

Found a good article on the /3GB switch:

http://blogs.technet.com/askperf/a [...] g-3gb.aspx

I am guessing you are on 32 bit Vista and the games you are running are written for 32 bit OS (XP or Vista) or run in 32 bit compatability mode on x64 systems. The performance test you are running as part of the game application is reporting the amount of memory available to the application (the game) and not the total memory in the system. The Vista kernel is constrained by default to 2GB, or half the total 32-bit virtual address space, with the other half reserved for use by the process whose thread is currently running on the CPU (the game).

Do not use the /3GB switch unless your application has been written to use more than 2GB memory (not common) as you will reduce the memory the OS has and your application will not benefit.

Your system is working normally.