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

---

• 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

 

[Bare Foot Kid]

Hello Dave, thanks!



Some do have issues with drivers, still.

 

[yowanvista]

Is there any performance gain by enabling AHCI ?

 

[Bare Foot Kid]

Is there any performance gain by enabling AHCI ?

Yes, search Google for benchmarks!

 

[yowanvista]

Just enabled it but my WEI score dropped from 5.9 to 1.0

 

[Jonathan_King]

Just enabled it but my WEI score dropped from 5.9 to 1.0

Don't worry about the WEI score. You can try running it again if you want, but it really doesn't make any difference.

 

[Bare Foot Kid]

Just enabled it but my WEI score dropped from 5.9 to 1.0

Is this how you re-ran the assessment?

 

[yowanvista]

Just enabled it but my WEI score dropped from 5.9 to 1.0

Is this how you re-ran the assessment?

View attachment 65517

I switched back to IDE because AHCI was making my PC slower. (PC took 20-35 secs more to boot)

 

[Bare Foot Kid]

Maybe you should have a look at the tutorial at the link below on how to optimize Windows 7 to see if it speeds you up; there's a lot of good info in there.

http://www.sevenforums.com/tutorials/11728-optimize-windows-7-a.html?ltr=O

 

[yowanvista]

Maybe you should have a look at the tutorial at the link below on how to optimize Windows 7 to see if it speeds you up; there's a lot of good info in there.

http://www.sevenforums.com/tutorials/11728-optimize-windows-7-a.html?ltr=O

Thanks but I'll stay with IDE. AHCI caused performance issues with my HDD.

 

[Bare Foot Kid]

Maybe you should have a look at the tutorial at the link below on how to optimize Windows 7 to see if it speeds you up; there's a lot of good info in there.

http://www.sevenforums.com/tutorials/11728-optimize-windows-7-a.html?ltr=O

Thanks but I'll stay with IDE. AHCI caused performance issues with my HDD.

OK mate, thanks for the update.

 

[Samcro]

Thanks BFK!
Everything went as described in the tutorial.
This was something I was looking to do as I had forgot to do this prior to the OS install. (1st build in many years and too many other things to check!)
My WEI, FWIW, went from 7.6,7.6,7.0,7.0,5.8 to 7.6,7.5,7.1,7.1,5.9, and boot time decreased by 5 seconds. Not meaningful changes by any means, but every bit helps especially under a full load.

 

[Bare Foot Kid]

Hello Samcro.



I'm pleased it could be a help to you!

 

[architect]

enable ahci with existing raid0

Hello to all,

here is MY problem:

i have raid0 with win7 running, all ok.
now i want to activate ahci;
if i activate it in bios, i have 4 sata drives appearing in bios,
but windows does not boot;
how can i solve this issue?

thanks!

 

[Jonathan_King]

First, did you change the registry key first?

I suspect that if you are using hardware RAID (which you are), you need to have your setting on RAID.

If you don't mind breaking the array, you could use a software RAID, like Windows striping and mirroring.

 

[architect]

hello,
isnt it possible to have raid and ahci activated at the same time??

 

[Jonathan_King]

hello,
isnt it possible to have raid and ahci activated at the same time??

Sorry, architect, it's one or the other. In your BIOS, you have to choose how the computer interacts with the hard disk controller. It can't choose to both interact with it as RAID, and as AHCI or IDE at the same time.

 

[architect]

thanks for the info.

 

[atlcraig]

I have already installed Windows 7 some time ago and just found out about AHCI. Can I follow these setps and have AHCI working when I am done or are there other things that I must do? Also is there a chance that Windows 7 will not work if I follow all the steps? Thanks for the help, atlcraig

 

[Jonathan_King]

Welcome!

Changing this registry setting will not hurt anything. All it does is enable AHCI, not force it.

If you want to switch to AHCI in your BIOS, you first need to enable it in Windows, or it will not boot.

No problems are foreseen; however, as always, if you have any problems, let us know, and we'll walk you through how to fix it.

 

[Bare Foot Kid]

Hello atlcraig, welcome to Seven Forums!



It's always best to create a restore point first in case of any trouble.