How to enable AHCI mode after Windows Vista / 7 Installation

This issue is known by most tech guys all around the world: People make an install of Windows 7 on their newly bought SSD and afterwards find out that they will get better performance with AHCI-mode enabled.
If you enable AHCI after the install of Windows Vista/ Windows 7 the boot procedure will result in a Blue Screen. This is the result of the harddrive controller changing when you enable AHCI.

So is there a way to enable AHCI after the install of Windows Vista / 7?
The short answer is “yes”.
You will need to disable AHCI while performing the procedure, but you’ll be able to enable it afterwards and make Windows boot normally without Blue Screens.

Your question might be: “How do I do it?”. Well it’s pretty easy. Follow these steps and you’ll be running your computer in AHCI mode:

  • If you’ve already enabled AHCI, please go into your BIOS to disable it.
  • Let Windows Vista / 7 boot like it normally would
  • In the Start menu search field write: Regedit
  • Go to the registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\msahci
  • Right click on “Start” and  choose “Modify”
  • In the Value Data field enter “0” (zero) and click “OK”
  • Exit Regedit
  • Reboot the computer and enter the BIOS
  • Enable AHCI
  • Let Windows Vista / 7 boot up
  • Standard AHCI drivers will be installed, and you can now install the manufacturer AHCI drivers if you want.
  • Reboot the computer and you are done with enabling AHCI.


Disclaimer: I can’t be held responsible for any problems that might arise from following this guide.