AHCI (Advanced Host Controller Interface) enables native command queuing and hot-plugging through SATA host controllers (Serial-ATA) for your hard drives. In many scenarios, it enables more efficient multi-tasking. Vista was the first Windows OS to support AHCI out of the box, whereas Windows 7 does the same. But an issue with AHCI is that if you install the OS without enabling AHCI in the BIOS, enabling it after installation will render your OS unusable. This is because Windows disable the AHCI driver since it is not needed during the installation.
There is one way to fix this, although you need to have knowledge of registry editing. The detailed steps from Microsoft are as follows:
To resolve this issue, enable the AHCI driver in the registry before you change the SATA mode of the boot drive. To do this, follow these steps:
- Exit all Windows-based programs.
- Click Start, type Regedit in the Start Search box, and then press ENTER.
- If you receive the User Account Control dialog box, click Continue.
- Locate and then click the following registry subkey:HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMsahci
- In the right pane, right-click Start in the Name column, and then click Modify.
- In the Value data box, type 0, and then click OK.
- On the File menu, click Exit to close Registry Editor.
After this you’ll have to restart your computer, go to BIOS and enable AHCI. When you log in to Windows again, you’ll notice the installation of drivers for AHCI. Another restart will be required to finish the driver installation.
I’ve simplified the steps by Microsoft by exporting the registry key. Just download the following file and run it. You’ll still need to go through the steps of restarting your computer and enabling AHCI in the BIOS.
Hopefully, you’ll find a somewhat noticeable improvement in multitasking, especially if you’re a notebook user. Of course with the variety of PC hardware, experience many vary.
Disclaimer:
It has an Extension of .REG same goes true for all Registry Files.
Start
Run/Start Search
Type: REGEDIT
Go to the following:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
Double Click “START” on the right Pane change the Value to “0” Reboot. And Enable ACHI in your BIOS either F1,F2,Del, F10 Depending on your Mobo.
What if the option to change from sata to ahci in BIOS is not present? Is there another way? Any help would be fantastic.
http://support.microsoft.com/kb/922976
Check the link, just download the file and install it.. Then restart. Go to BIOS change to AHCI, save and exit. Windows will load and start installing the drivers… you are done..
Excellent, thanks
If someone has a mainboard that has a secondary SATA controller, such as JMicron, all they need to do is attach their boot drive to one of the other connectors. They can then change the SATA setting in the BIOS (which *only* affects the main SATA controller), boot, and install the AHCI drivers as any other new hardware. Once the drivers are install, power off, re-attach the boot drive to the main SATA connectors, and reboot. No need to futz around with the registry … :-).
PS. This is assuming they’ve already installed the drivers for the secondary SATA controller (which some people forget to do).
worked great, needed this after installing OSX on my pc
hi all
my main Asus P7P55D chip intel P55. HDD santa 2. OS Win 7 64 bit RC
I trying convert mode Santa –> AHCI..failed !!! :
Setup new install OS …not dectect HDD..
after install OS with mode IDE . I run regedit :
HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMsahci
I change mode in BIOS : IDE –> AHCI. reset my computer not success
please help me…
I did it with success, my intel x25 160 has windows 7 rating from 7.4 with IDE to 7.7 with AHCI. Yay!!!!