How to enable UDMA66 mode on Intel chipsets

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Article ID: 247951 - View products that this article applies to.
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By default, the UDMA66 mode is disabled on a computer that is running Microsoft Windows when the computer uses a Intel chipset that supports UDMA66. This behavior is by design.

Enable the UDMA66 mode

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 How to back up and restore the registry in Windows
  • Make sure that the device supports UDMA66 mode.
  • Use an 80-pin IDE cable with the correct pin cut.
  • Add the following registry key:

    1. Start Registry Editor.
    2. Locate the following key in the registry:
    3. On the Edit menu, click Add Value, and then add the following registry value:
         Value Name: EnableUDMA66
         Data Type:  REG_DWORD
         Value:      1				
    4. Quit Registry Editor.
    5. Restart the computer.
Note For more information about the IDE cable, contact the hardware manufacturer.

When you restart your computer, the UDMA66 mode will be enabled if the mode is supported by the hardware.


Article ID: 247951 - Last Review: August 18, 2005 - Revision: 5.2
  • Microsoft Windows 2000 Server
  • Microsoft Windows 2000 Advanced Server
  • Microsoft Windows 2000 Professional Edition
  • Microsoft Windows XP Professional
  • Microsoft Windows XP Home Edition
  • Microsoft Windows Server 2003 Service Pack 1
kbhowtomaster kbstoragedev KB247951

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