AHCI : Enable in Windows 7 / Vista

AHCI : Enable in Vista and Windows 7 after OS install​

   Information

AHCI Advanced Host Controller Interface makes NCQ Native Command Queing along with hot-plugging or hot swapping through SATA Serial-ATA host controllers possible; Vista was the first to offer this feature. The issue with AHCI is it needs to be enabled in the BIOS prior to OS installation; doing so after you have installed the OS will disable the PC. The reason why is Windows disables the AHCI drivers not needed durring installation.

This tutorial will show you how to enable AHCI after you have installed the OS if you didn't already have AHCI enable in the BIOS when you installed the OS.

   Warning

Changing values in the Windows registry can disable your machine; if you're not sure how to do this please post a question in this tutorial and someone will be glad to help you.

   Note

This method will also work for Windows Vista though the default DWORD string value in Vista will be "4" where it will be "3" in Windows 7.

As a precaution it would be a good idea to create a "System Restore Point" before you start this, the tutorial can be found at the link below.

System Restore Point - Create

Let's get started!
1) In the Windows start menu search box type regedit, right click the entry, click Run as Administrator, enter your user credentials for the UAC prompt, then click yes to open regedit.



2) In regedit navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services.

3) In the left pane, click on msahci, in the right pane double click on Start to modify it.


4) In the window that opens change the value to 0 (zero), and click OK.

5) In the left pane, click on iaStorV (if there), in the right pane double click on Start to modify it. Repeat step 4, and go to step 6 below.
NOTE: From: Error message occurs after you change the SATA mode of the boot drive

6) Close Registry Editor.
7) Now you'll need to restart the PC and go into the BIOS and enable AHCI. When Windows boots up, it will finish installing the AHCI drivers.



8) You will need one final restart to finish the process after the drivers are installed.

   Note

For those with nForce boards, have a look at the Information post below.

The method was worked out by Everlong and credit for that goes to him, thanks mate!

Enjoy!

Related Tutorials

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• How to Enable AHCI in Windows 8 and Windows 10 after Installation
• How to Enable HIPM and DIPM for your SSD and HDD in Windows 7

 

[swarfega]

It might be an idea to add a statement to the tutorial saying that it would be a good idea to create a restore point before doing this.

 

[Bare Foot Kid]

It might be an idea to add a statement to the tutorial saying that it would be a good idea to create a restore point before doing this.

Hello Nick, I meant to do that and got side tracked, I'll do that after work today; thanks for reminding me.

 

[Bare Foot Kid]

Update: a link to the system restore point tutorial has been added.

 

[wysiwyg]

Hello wysiwyg.

Is there something like "storage configuration" or something similar?

Found s/con on MAIN in Bios, AHCI doesn't show until you change IDE to AHCI,

Did all requirements but I wondered why I bothered for the difference it made.



The only difference is
Cpu up from 7.3,
Ram up from 7.5

Graphics and Disk no difference.

 

[nate42nd]

Thanks for the info BFK

I always install Windows 7 in AHCI mode. I have found this will allow me to switch between IDE and AHCI.....it seems to work great, but sometimes people don't have the option or it comes pre-installed. This is great information.

 

[Bare Foot Kid]

Hello wysiwyg, I'm glad you got it sorted.




Hello Nate, this is the first I've run AHCI.

 

[nate42nd]

Hey BFK, I have run tests switching between the two settings with my hard drives and SSDs. They are just a bit faster on AHCI but you do have "hot plugging" and other things with AHCI.

Patriot recommends IDE for their SSDs right now, and some of the firmware updates and performance restore utilities don't run very well in AHCI

Anyway, thanks again for this info

 

[Bare Foot Kid]

Hello Nate, thanks for your info; hot plugging is what I'm interested in.

 

[nate42nd]

This is an interesting page. Native Command Queuing is another benefit.

AHCI vs IDE ? Benchmark & Advantage Expertester

 

[CarlTR6]

Very nice and thank you.

 

[Bare Foot Kid]

Thanks Nate and Carl.

 

[Capt.Jack Sparrow]

Nice Tutorial BFK !!

 

[thefabe]

Nice job On the tutorial Ted.

 

[Bare Foot Kid]

Thank you CJS and Fabe.

 

[Kipper]

Thanks barefoot

Worked perfectly

 

[Bare Foot Kid]

Hello Kipper, I'm glad it worked for you!

 

[golem]

Ok, I knew I'd have a hiccup attempting this. During install of my OS a few weeks ago I tried to enable AHCI but kept failing boot so I just stuck with IDE and all has been working well. Figured why not give it a try now that everything is running smoothly. I added a restore point, modded the reg then enabled AHCI in the bios. Upon reboot BIOS starts listing the HD's then as the rest of that particular page is rendering I notice the primary drive listing disappears. Towards the end of BIOS initialization I'm greeted with a notification that no OS is available to boot.

After double checking that I hadn't inadvertently change something I shoulden't have in the BIOS I decided to do a "System Restore" via "System Recovery" off the retail disk. Unfortunately when I get to the System Recovery's option of choosing which OS the apply the restore point to I have no OS to choose from. For some reason it's not detected.

Any suggestions?

 

[Bare Foot Kid]

Hello golem, welcome to Seven Forums!


If you can get into safe mode (F8 on bootup) choose the "Last Known Good" option; or in safe mode in regedit can you change the value back to "3"?

 

[golem]

Thanks for the welcome!

Nope, safe was my first stab at getting back. Seems the OS is completely AWOL.

I've gone back again and checked BIOS. Everything looks in order in addition to the SATA option being switched back to IDE. Even rechecked all my HD connections since I did have to swap a data drive for a DVD drive because I could never get it to work via USB. Guess I should add the only REG mod was to the "Start" value from 3->0

Cheers!

 

[Bare Foot Kid]

Thanks for the welcome!

Nope, safe was my first stab at getting back. Seems the OS is completely AWOL.

I've gone back again and checked BIOS. Everything looks in order in addition to the SATA option being switched back to IDE. Even rechecked all my HD connections since I did have to swap a data drive for a DVD drive because I could never get it to work via USB. Guess I should add the only REG mod was to the "Start" value from 3->0

Cheers!

Did you switch the SATA cables (at the mobo) around?