So I am guessing you are here for one reason, you are trying to enable AHCI on your BIOS when you installed Windows while only IDE was enabled within your BIOS?. Well, here is how to fix it. At first, I didn’t think it was that big of a deal. I just got a Core i7 860 and an ASUS Maximus III Formula motherboard, and had to reinstall Windows 7 obviously. But I had IDE mode set for the Storage settings in the BIOS, which was automatically set at that so I didn’t think about setting it to that in the first place. So, after installing Windows 7… my friend tells me “enable AHCI mode in your BIOS”. I was like “uh, okay”. I got the blue screen of death. I was stumped, didn’t know what to do. So I Google searched it and found out how to fix the problem, allowing me to enable AHCI without Windows crashing at boot each and every time.
The main point in enabling AHCI is apparently it speeds up the boot process in Windows. Mine was kind of slow and that’s what made him bring it up in the first place. Either way, if I didnt have issues or not I still like my computer running in the settings that are supposed to be set at.
And a little more background information regarding AHCI. In your system BIOS, turning on AHCI allows or I should say “enables” NCQ (Native Command Queuing) which is hot-swapping of the current-gen SATA hard drives. And turning on AHCI with the SATA drives that indeed support NCQ will give much better speed and performance in many cases in making the drive to take advantage of the order of read and also write requests given on the position of the platter itself, which lessens the head movement and also allows the drive to give out requests in much fewer rotations gradually overtime.
Though, AHCI should be turned on in the BIOS just before the installation of the operating system installation. If you turn AHCI on just after you have installed the OS already, it will cause a BSOD symptom which you came here in the first place to fix. And this is mainly happening because Windows turns off the AHCI drivers that are not needed during the installation, and so if you turn on this feature the driver will not be there during the boot process of Windows and the OS will crash. And for Windows 7 and Vista there is a simple fix.
First, back up your Windows Registry. This can be done by:
1. Go to Start (the Windows logo at the bottom left of the screen) and click on it, then type “regedit” and press ENTER.
2. Click “Yes” when that confirmation window pops up and makes the annoying “beep” noise.
3. Click on “Computer” in the left column, then go to File, Export.
4. Save the registry to your Desktop for convenience purposes, and name it whatever you want.
Done, now your Windows Registry is backed up.
Now to enable AHCI in Windows.
1. Close all of your running applications in Windows (I kept Firefox open and was fine).
2. Go to Start again and do the same as before, type in “regedit” in the search field and press ENTER.
3. Click “Yes” when the confirmation window pops up again.
4. Go to the follow Registry subkey: HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMsahci
5. In the very right hand side pane, right click on Start in the Name column and then click on Modify.
6. In the Value data box, type in “0″ and then click on OK and close the Registry Editor.
7. Restart your PC while being prepared to press the key that brings you into your BIOS settings. For me it was the Delete key.
8. After booting into Windows successfully, a new driver will be installed for the AHCI drivers and you will be prompted to reboot your OS just one more time to finalize everything.
And you just have done what Einstein couldn’t achieve because he didn’t live long enough to use computers today, you completed the fix that allows you to not have to reinstall the OS to just enable AHCI!.