You cannot put a computer that is running Windows XP, Windows Server 2003, Windows Vista, or Windows Server 2008 into hibernation. Additionally, the Hibernate tab in the Power Options Properties dialog box is unavailable.

Notes

•	This issue occurs if your computer has more than 4 gigabytes (GB) of random access memory (RAM).
•	This issue occurs in both 32-bit and 64-bit versions of Windows.

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This issue occurs because hibernation is disabled on computers that have more than 4 GB of RAM.

Hibernation requires sufficient disk space to contain the contents of the computer's memory. Performance is poor on a computer that has more than 4 GB of memory and that has support for hibernation. Therefore, Microsoft has disabled support for hibernation on such computers.

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To work around this issue, decrease the RAM to 4 GB or less on a computer that is running Windows XP, Windows Server 2003, Windows Vista, or Windows Server 2008.

Note Sometimes, the Hibernation tab is unavailable even after you decrease the RAM to 4 GB or less. This issue occurs because PCI memory resources are mapped in the middle of 4 GB physical memory address spaces, and the rest of the RAM is mapped to more than 4 GB of physical memory address space. If the value of the highest physical memory address is larger than 4 GB, Windows determines that the computer has more than 4 GB of memory. Therefore, the Hibernation tab is disabled. In this scenario, you must add the /MAXMEM=4096 switch to the Boot.ini file to reduce the highest physical memory to 4 GB.

For more information about the MAXMEM switch, click the following article number to view the article in the Microsoft Knowledge Base: To work around this issue on a computer that is running Windows Vista, enable hibernation. To do this, run the following command as an administrator: To do this, follow these steps:

1.	Log on as an administrator.
2.	Click Start, type cmd in the Start Search text box, right-click cmd.exe, click Run as administrator, and then click Continue.
3.	At the command prompt, type powercfg –h on, and then press ENTER.

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To view the Power Options Properties dialog box, click Start, click Run, type powercfg.cpl, and then click OK.

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Technical support for x64-based versions of Microsoft Windows

If your hardware came with a Microsoft Windows x64 edition already installed, your hardware manufacturer provides technical support and assistance for the Windows x64 edition. In this case, your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation by using unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with a Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware. If you purchased a Windows x64 edition such as a Microsoft Windows Server 2003 x64 edition separately, contact Microsoft for technical support.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site: For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site:

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