Can I enable AHCI after installing Windows 7 in a SATA drive that was on IDE mode?


You need to make the msahci and/or IastorV drivers be loaded early.

(Note: For Windows 10, the built-in driver is called storahci.)

According to Microsoft KB 922976, run Fix it 50470 or open regedit, navigate to one of these keys:

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV

and set the value of the Start dword to 0.

using regedit to enable AHCI mode in Windows 7

Reboot and enable AHCI in BIOS, now it should work.

Remember to create a restore point before any changes, just in case.

The same registry changes can be done via Cmd, using reg add or sc config:

  • Check current parameters (and make sure the service exists):

    sc qc msahci
  • Change the boot mode:

    sc config msahci start= boot

    (Note that start= is a single parameter, but boot is separate.)

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    It only worked when I followed your procedure. – Jader Dias Feb 20 '10 at 2:36

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