Change from Legacy IDE Mode to AHCI Mode without Having to Rebuild

We still have some systems in the environment that the default bios setting are to have the SATA controller set to run in legacy Parallel ATA emulation mode. The other day a system was built with Windows 7 but the bios setting was not changed and therefore was running in AHCI mode. Most would concede that the system would need to be rebuilt, but alas a solution thanks to Marc Pottratz.

1. Enable AHCI Driver in the registry
   
   1. Locate and then click one of the following registry subkeys:
      

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
   

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV
   

   1. In the right pane, right-click Start in the Name column, and then click Modify.
      
   2. In the Value data box, type 0, and then click OK.
      
2. Install the standard Microsoft AHCI driver.
   
   1. Open device manager and locate the IDE/SATA controller.
      
   2. Open the controller's properties and on the driver tab select Update Driver.
      
   3. Select Browse my computer for driver software.
      
   4. Select Let me pick from a list of device drivers on my computer.
      
   5. Uncheck Show compatible hardware.
      
   6. Scroll down the Manufacturer column and select the Standard AHCI driver.
      
   7. Click next and this should install the Microsoft AHCI driver.
      
3. Reboot and then change your bios settings over from IDE configuration to AHCI.
   
4. Install the appropriate AHCI driver for your motherboard.