A description of the differences between 32-bit versions of Windows Vista and 64-bit versions of Windows Vista

This article describes the differences between the 32-bit versions of Windows Vista and the 64-bit versions of Windows Vista.

Note To use a 64-bit version of Windows Vista, you must have a computer that has a 64-bit processor. Also, you must have 64-bit device drivers for the devices that are in the computer.

You may want to determine whether the platform of Windows Vista is installed.

To have us help you determine which platform is installed, go to the "Fix it for me" section. If you would rather fix this problem yourself, go to the "Let me fix it myself" section.

Fix it for me

To determine which platform is installed automatically, click the Fix this problem link. Then click Run in the File Download dialog box, and follow the steps in this wizard.



Note This wizard may be in English only; however, the automatic fix also works for other language versions of Windows.

Note If you are not on the computer that has the problem, you can save the automatic fix to a flash drive or to a CD, and then you can run it on the computer that has the problem.

Let me fix it myself

To determine which Windows Vista platform is installed yourself, follow these steps:

1. Click Start, right-click Computer, and then click Properties.
2. The operating system appears as follows:
   • For a 64-bit version operating system, "64-bit Operating System" appears for the system type under System.
   • For a 32-bit version operating system, "32-bit Operating System" appears for the system type under System.

Note Microsoft Win32 uses the x86 processor in 32-bit flat mode. Therefore, a x86-based version means a 32-bit version operating system.

The main differences between the 32-bit versions of Windows Vista and the 64-bit versions of Windows Vista relate to memory accessibility, memory management, and enhanced security features. The security features that are available in the 64-bit versions of Windows Vista include the following:

• Kernel Patch Protection
• Support for hardware-backed Data Execution Protection (DEP)
• Mandatory driver signing
• Removal of support for 32-bit drivers
• Removal of the 16-bit subsystem

One of the greatest advantages of using a 64-bit version of Windows Vista is the ability to access physical memory (RAM) that is above the 4-gigabyte (GB) range. This physical memory is not addressable by 32-bit versions of Windows Vista.

Depending on the version of Windows Vista that is installed, a 64-bit version of Windows Vista supports from 1 GB of RAM to more than 128 GB of RAM. The ability to address more physical memory lets Windows Vista minimize the time that is required to swap processes in and out of physical memory. Therefore, Windows Vista can manage processes more efficiently. This memory management feature helps improve the overall performance of Windows Vista.

Advantages when you install a 64-bit version of Windows Vista

• Increased memory support beyond that of the 4-GB addressable memory space that is available in a 32-bit operating system
• Increased program performance for programs that are written to take advantage of a 64-bit operating system
• Enhanced security features

What to consider when you install a 64-bit version of Windows Vista

• 64-bit device drivers may not be available for one or more devices in the computer.
• Device drivers must be digitally signed.
• 32-bit device drivers are not supported.
• 32-bit programs may not be fully compatible with a 64-bit operating system.
• It may be difficult to locate programs that are written specifically for a 64-bit operating system.
• Not all hardware devices may be compatible with a 64-bit version of Windows Vista.

The main differences between the 32-bit versions of Windows Vista and the 64-bit versions of Windows Vista

For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
For more information about 64-bit versions of Windows Vista, visit the following Microsoft Web site: