For This Vot133, I Upgr Rama To 4gb, But Usable Mem Is At 2.62 Gb In Win 7 Pro,.

4GB address space (64-bit versions can use much more). That's the

theoretical upper limit beyond which you can not go.

But you can't use the entire address space. Even though you have a 4GB address space, you can only use around 3.1GB of RAM. That's

because some of that space is used by hardware and is not available to

the operating system and applications. The amount you can

use varies, depending on what hardware you have installed, but can

range from as little as 2GB to as much as 3.5GB. It's usually around

3.1GB, but in your case it's somewhat less.

Note that the hardware is using the address space, not the actual

RAM itself. If you have a greater amount of RAM, the rest of the RAM

goes unused because there is no address space to map it to.

This is a feature, not a bug. Although 32-bit versions of Windows have a 4 GB address space for memory, some of those addresses are used for various hardware devices installed in your computer. Any "memory address" used for a piece of hardware is not available as an address for your RAM. Thus, although your system can install 4 GB of RAM, the amount of RAM actually addressable (i.e., usable) by Windows will be somewhat less.

With 4 GB of physical RAM installed, the usable RAM often is around 3.2 GB, but perhaps you have a video card that has a lot of built-in RAM (which needs the address space, even if it has its own physical memory chips) or perhaps you have several PCI or PCIe cards that use memory address space.

If you want to have more RAM available for Windows, you'll need to switch to the 64-bit version of Windows 7.

See this article for more details --> http://web.archive.org/web/20101111232219/http:/members.cox.net/slatteryt/RAM.html

Thanks