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:
Worked fine on my Asus P6T SE with a Corsair P64 ssd under Windows 7 Home Premium 64 bit.
The windows performance index went from 7.1 to 7.3
Thanks!
Hi All,
I tried doing the same thing for my Fujitsu Amilo si 3655 with windows 7 OS. The setting in registry is already 0.
When i looked into BIOS and trying to enable Sata drive it is in non editable mode.
I am very new to all these settings so probably I might be looking at some wrong place. Please let me know where exactly do I need to go to enable the AHCI mode.
Thanks for the tip, worked fine for me on my EVGA E758-A1
did not work for me on a p6t / i7950 / win7 ultimate x64 ….. changed the registry, enabled ahci in bios and got a bsod when starting windows …
Mine hasn’t been working, so I would like to change it back.
When you right click on start, in the “Msahci” and change the number to 0, what was it originally?
I would like to change everything back to how it was before I tried this, as whenever I tried booting into windows, I would get a BSOD.
So yes, what was the number before you are suppose to change it to 0?
the original value is 3 … I did also revert the registry to its initial value for that matter and it worked fine!
It worked flawlessly on an old Acer 4715Z notebook.
Thanks a lot!
On my ASUS P5KC the registry script works fine.. No bluescreens.. However when I attempted to switch from SATA to AHCI it is no longer there..
I will have to revert and figure out what is going on..
It might be because I have 3 drives now installed.. I am so confused.. Oh well might just wait for reinstall time etc..
I just went from a 7.1 to 7.6 score for my primary hard disk using Windows 7 “Windows Experience Index” test.
This worked out great, thanks for the info!
Thanks alot! This worked perfectly on my Windows 7 retail OS and Gigabyte EP45-UD3P board.
I tried same thing in Windows 2008 and it did work. This post saved my whole day. Thank you very much and keep going.
Thanks very much.
It worked on my Thinkpad X100e
^^b
Dude, this worked perfectly IOU a large cold beer!
glad to be of help :)
You rock! Thank you.