How to enable AHCI in Windows 7 RC after installation

Windows

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:

  1. Exit all Windows-based programs.
  2. Click Start, type Regedit in the Start Search box, and then press ENTER.
  3. If you receive the User Account Control dialog box, click Continue.
  4. Locate and then click the following registry subkey:HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMsahci
  5. In the right pane, right-click Start in the Name column, and then click Modify.
  6. In the Value data box, type 0, and then click OK.
  7. 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. enable ahci in Windows 7

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:

Beware, though, you’re responsible on your own for messing around with the registry. This guide comes with no warranties if your computer blows up, gets angry at you, stops working or just shows a Blue Screen of Death.
About the Author

Technology enthusiast, Internet addict, photography fan, movie buff, music aficionado.

243 comments

  1. Thank you for the post. Unfortunately it caused instability in my particular case, maybe there are additional settings in BIOS to deal with? or the native windows driver isn’t the best choice? changing the registry item back to 3 and going back to IDE mode in BIOS seems to work.

  2. Thankyou so very much for this!!!! Im running Win7 x64 and the instructions worked perfectly!!

  4. this reg file is not quite same as this post?

    1. HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci

    2. HKEY_LOCAL_MACHINE\System\ControlSet001\Services\Msahci

    am I wrong ?

    1. I agree post itself and .reg file have different registry keys listed.
      Which one to use?

  6. Thank you very much for sharing this info, worked perfectly for me after I installed a new motherboard and wanted to use the AHCI settings.

    Thanks!

  8. Does this patch work on a windows XP box ?
    My mobo bios does have ahci between the options, but for xp to recognize the disk, I needed to keep this options as ‘sata’ because if I select ‘ahci’ the installation procedure said there is no hard disk!
    So, now and after a successfull installation of xp, I wish to change it to ‘ahci’, but up to now, to no avail.
    Regards,

  10. Hey – thanks for the tip. Do you know if this will work going from AHCI to RAID? If so, do you know the value to enter?

  11. Pingback: ECS P45T-A(P45+ICH10R) wouldn't able to enable UDMA6!! - Overclock.net - Overclocking.net
  12. Pingback: ECS P45T-A(P45+ICH10R) wouldn't able to enable UDMA6!! - Page 2 - Overclock.net - Overclocking.net

  15. Thanks a bunch…will be trying this out on my home PC this weekend. Also thanks because this helped resolve an issue on my work PCs.

  16. Thanks a bunch…will be trying this out on my home PC this weekend. Also thanks because this helped resolve an issue on my work PCs.

  17. Hello,

    Despite your detailed walkthrough, I had to stick to Compatibility on my ThinkPad X60 with a Kingston SSD. Just didn’t go past POST if I turned on AHCI.

  18. Hello,

    Despite your detailed walkthrough, I had to stick to Compatibility on my ThinkPad X60 with a Kingston SSD. Just didn’t go past POST if I turned on AHCI.

  19. Hello,

    Despite your detailed walkthrough, I had to stick to Compatibility on my ThinkPad X60 with a Kingston SSD. Just didn’t go past POST if I turned on AHCI.

  20. Pingback: Is this a good SSD? - Page 2 - Overclock.net - Overclocking.net

Comments are closed.