- Exit all Windows-based programs.
- Click Start, type regedit in the Start Search box, and then press ENTER.
- If you receive the User Account Control dialog box, click Continue.
- Locate and then click one of the following registry subkeys: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsahciHKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV
- In the pane on the right side, right-click Start in the Name column, and then click Modify.
- In the Value data box, type 0, and then click OK.
- On the File menu, click Exit to close Registry Editor.
For example, assume that you install Windows Vista or Windows 7 on a computer that contains a controller that uses the Pciide.sys driver. Later, you change the SATA mode to AHCI. Therefore, the drive must now load the Msahci.sys driver. However, you must enable the Msahci.sys driver before you make this change.
This issue affects only the boot drive. If the drive that you change is not the boot drive, you do not experience this issue.
AHCI provides several features for SATA devices. These include hot plug functionality and power management functionality. For more information about the AHCI specification, go to the following Intel website: Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.