Setting your system drive to AHCI

It may happen that you discover that your preinstalled Windows isn’t set to use AHCI on hard disks or SDDs.

If you simply commute the BIOS settings, the OS will not be able to be loaded anymore.

Looking for solutions, I found the following ones:

Windows 10

According to this page (at http://www.tenforums.com), mainly you have to:

  • setup windows to run in safe mode on the next reboot
  • update the BIOS setting
  • restore windows to normal mode, and reboot again.

From a Command Prompt with Admin privileges:

  • to set the safe mode on the next boot, you have to type the following:
bcdedit /set {current} safeboot minimal

to set back the normal mode on the next boot:

bcdedit /deletevalue {current} safeboot

Windows 10 + 8.x

From this page (at http://www.tenforums.com), the approach is a little more complex.

We have to update the following values into the registry as follows:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
+ iaStorAV\StartOverride
   key: 0
+ iaStorV
   key: Start
+ storahci
   key: Start
+ storahci\StartOverride
   key: 0

Update the values above to 0.

Reboot, and update BIOS configuration, and follow Windows instructions.

Windows 7 + Vista

From this page (at http://www.sevenforums.com), the approach is similar to the previous one but on different registry keys.

We have to update the following values into the registry as follows:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\
+ msahci
   value: Start
+ iaStorV
   value: Start

Update the values above to 0.

Reboot, and update BIOS configuration, and follow Windows instructions.

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