Switch RAID to AHCI without reinstalling Windows 10

My Dell XPS 9560 uses RAID as a SATA controller mode.

After I change it to AHCI, the Windows 10 will not boot.

What should I do if I don't want to reinstall Windows 10?

_{RAID = Redundant Array of Inexpensive Disks, wikipedia link.
AHCI = Advanced Host Controller Interface, wikipedia link.}

Solution 1:

You need to install the correct driver for your AHCI storage controller before changing the mode in the BIOS.

If you don't do so, after switching the mode Windows cannot load the storage controller driver needed to access the boot volume. Because this driver is loaded before the Plug and Play Manager, Windows can't automatically detect or otherwise search for the correct driver.

Pre-installing the driver should solve this.

That said, you don't mention the reason you want to do this, but if it's for reason of performance, in my experience there's no difference between the two modes on Dell XPS machines.

Solution 2:

There is actually another way around this. Before you begin, make sure you remember your PC password (not PIN), or else you would be stuck in safe mode forever (with this way of entering safe mode). Also, I advise you to disable BitLocker before entering safe mode, or else you would probably need to provide a very long code to unlock your computer (not tested).

Booting into Safe Mode will work even though the storage mode has been changed... Windows will notice the change and load the correct driver on the next normal boot. Basically that means, you can do this:

1. Run cmd as administrator (not PowerShell, you would have to escape {...})

2. Copy-paste this command, which will start Windows in Safe Mode the next time you reboot:

   bcdedit /set {current} safeboot minimal
   

3. Restart the computer and enter UEFI/BIOS setup.

4. Change the SATA operation mode from RAID to AHCI.

5. Save changes and exit Setup and Windows will automatically boot to Safe Mode.

6. Launch cmd again, as in step #1.

7. Copy-paste this command, which will start Windows in Normal Mode the next time you reboot:

   bcdedit /deletevalue {current} safeboot
   

8. Reboot and Windows will automatically start with AHCI drivers enabled.

Note: Switching to AHCI is essential if you want to install any Linux as RAID mode is to my knowledge not supported, so you would not see your drive(s) in the installation menu.

Solution 3:

Warning: If you have bitlocker enabled, save your recovery key elsewhere (or write it on paper) before attempting to change to AHCI. You will need it for safe mode boot.

If windows fails to boot three times, it lets you boot into safe mode. When it shows the Choose an option screen, get to safe mode: Troubleshoot -> Advanced Options -> Advanced Startup Options -> Startup Settings -> Restart. Once restarted, choose 4 (safe mode).

Once the computer has booted into safe mode (and automatically installed the AHCI driver), you are free to restart normally.