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.
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243 comments

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  8. HOLA, TENHO UM PC COM GIGABYTE G31M-S2L  CORE2 DUO E7200, 3GB KINGSTOM, HD 500 GB, XFX 5750. DÁ PRA INSTALAR O MAC OS X SNOW LEOPARD NO MEU PC?

  11. Thanks I did this and it worked. Now I have a problem though; 8 out of 10 times my computer will boot up to go into BIOS right away. I need to enter ‘discard changes and exit’ for it to boot up to Windows. Very anoying because I bought an SSD just so my computer would be (and boot up) faster. 
    Does anyone know how to fix this?  I tried flashing my bios, and changing the sata cables of my 2 drives around. 

    Thanks in advance : 

    Intel core i5-2320 @ 3.00GhzWIN7 64b sp18 gig ramgtx 560 bios: MSI H61M-E33 (B3) bios v10.141st drive SSD OCZ-AGILITY3 120g 
    2nd drive: some old (but good working Seagate sata 2, 3ghz , 220g   drive) 

  15. Just installed a samsung SDD 840, ASUS M3A78-EM mother board, could not for the life of me get AHCI to run right. Spent a couple of hours playing and updating my bios to no avail. Found this web site, tried this fix and voila!!! AHCI is now enabled and running!! Victory…Thanks for the great tutorial!!

    1. I’m right where you were Mike (but add a couple of hours)….I can’t wait to get home to try this! Will let y’all know.

  16. how come the path in the registry (if you do it manually) is different than the path it the .reg file you have for download?

  17. Well holy cow, it worked….Thank you Imran!! You have no idea how many days I’ve waisted reading other peoples spew, trying it, and failing…..sure wish I came across this sooner, but, it brought me from a 7.6 to a 7.8 on performance. Of course I had a couple of 6.0 etc…on the way to get here :(….But thanks again and keep it up…..please.

  19. Bless you!! I fought with this issue for a day and a half. Found your solution and fixed it in less than 5 minutes. I’ve saved your post and “fix” so when I have to do a reinstall down the road, it will be a cake walk next time.

  20. FYI:

    I followed your steps, however after I enabled AHCI in the BIOS after making the registry change and shutting down I still got the Blue Screen. Enabled IDE mode and booted normally. Confirmed the reg key was still set as mentioned above. This was on an 8440p EliteBook HP Notebook.

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