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

 

[WindowsStar]

@tweakradje

You can shorten all that to: Before you reboot and change the BIOS do this part as you listed

::Start

Make sure that the AHCI service is started during boot time. Goto HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\msahci and set Start to 0 (at boot time)

Now reboot and go into the BIOS to switch the controller mode from whatever to AHCI.
Save your BIOS settings and reboot.

::End

Make sure you press F8 and boot in to safe mode, install the correct driver, reboot. Your Done.

Clean up if you wish.

I have done this many many times works perfectly. -WS

 

[tweakradje]

Thanks for your info. I will test it on some pristine machines an let you know.

My experience so far is that the CriticalDeviceDatabase key must be present.

I let you know.

Cheers

 

[Clemmy Clem]

Thank you

@ Bare Foot Kid: Thank you for doing this. You have just saved me 2 days worth of re-installing files as I forgot to set my SSD to AHCI before I installed Windows 7.

You are a super star!!!

 

[jdavistdi]

Hello,

I think I'm beyond help for my situation, but this forum seems to have a lot of answers, so I'm crossing my fingers.

I have a very old Dell Dimension 8300 system (almost 9 years old) and I have a Samsung 330 SSD drive. I think that my system might be too old to support AHCI, but I thought I'd double check here, just in case.

I've followed all the instructions, but I simply cannot find any setting to change from IDE to AHCI.

Any ideas?

Regards -- James

 

[WindowsStar]

Hello,

I think I'm beyond help for my situation, but this forum seems to have a lot of answers, so I'm crossing my fingers.

I have a very old Dell Dimension 8300 system (almost 9 years old) and I have a Samsung 330 SSD drive. I think that my system might be too old to support AHCI, but I thought I'd double check here, just in case.

I've followed all the instructions, but I simply cannot find any setting to change from IDE to AHCI.

Any ideas?

Regards -- James

James - I don't think the Dell 8300 supports AHCI. Do you see it in the BIOS settings? As far as the SSD drive most/many backwards compatible so you could be able to use the drive without the need for AHCI drivers. However your problem is that this is a SATA III drive and your system only supports SATA II, if you can return it for a SATA II I would do that. -WS

 

[jdavistdi]

Thanks for the response. I believe I can still return the drive since I just purchased it a few days ago. I'll see if I can get a SATA II drive instead. I did not see an option in my bios to choose AHCI.

 

[Jatt50]

Good. It brought my ssd score from 7.4 to 7.7 with AHCI enabled on SATA 2 3gbps.

 

[notis]

..Just for saving time...
....Do I need to do anything (like this tutorial suggest), when I'll... "clean install" W7 over my OEM W7?
.........Thank you much much!...

 

[Brink]

Hello Notis,

Nope. This tutorial is for after installation. Since you'll be doing a clean install, you could just set your BIOS settings to use AHCI/SATA before the installation instead.

 

[notis]

...Thanks for reply...(my f...poor english...always!...)
..I meant.. :
.. now in my bios..is written -SATA operation [ACHI]. When I'll do a "clean install W7", a) will bios stay like it is now or I have to care about?
..and b) maybe (not sure), I'll update my bios from A13 to A19, then will I have to look for.. or settings will stay?
(never I did something else than restoring to factory settings...so excuse my simple questions...)
For admin.
-Is it possible someone to write in his "system spec" about two computers? Often I see confusion when I get a reply..

 

[Brink]

Ah, ok. No problem.

..I meant.. :
.. now in my bios..is written -SATA operation [ACHI]. When I'll do a "clean install Windows 7", a) will bios stay like it is now or I have to care about?

Your BIOS settings will stay set.

..and b) maybe (not sure), I'll update my bios from A13 to A19, then will I have to look for.. or settings will stay?
(never I did something else than restoring to factory settings...so excuse my simple questions...)

Sometimes flashing (updating) your BIOS firmware will reset the settings back to default, so you should double check them to make sure they are still set how you like afterwards.

For admin.
-Is it possible someone to write in his "system spec" about two computers? Often I see confusion when I get a reply..

There's just not enough room to have multiple "separate" system specs. However, if you have enough space, you could still type in the other systems specs within the same fields separated by say a dash.

It would be best to specify in the post which one you are having the issue with to help avoid confusion though.

 

[notis]

...Thanks....much...much..
so many "things" about computing ...are getting clear!...
....so many...."well made".....tutorials....
......You are ...REALLY......valueable!

 

[Brink]

You're most welcome notis.

 

[ZoltanGZ]

Wow that was a lot of posts !! 52 pages !

Hello all !
Just registered because I want to add my 2 cents worth on this topic, and get your views on my BIOS issues and registry values on my Win 7 Pro SP1 64.

I have been following this thread since the 2010 posting, and I see it's still going strong.
I have a fairly new Dell Studio XPS 8100, and a SATA Seagate internal hard drive, with a LaCie external eSATA backup. (1 TB SGate and 2 TB external).

In trying to determine whether or not I was in IDE or AHCI mode or whatever, I checked the registry and found that the values were for msahci = 3 instead of 0, and also the iaSTorV = 3 instead of 0.

So getting into the BIOS (America Megatrend?) the only setting options I found was ATA or RAID, and RAID was selected .. showing SATA 1 Drive, SATA 2 Drive, etc.

Now previous post here indicated that if RAID is selected, even though I do not have more than one internal HDD and is not really set up in RAID fashion, that it automatically puts the system into AHCI mode, and ATA would be IDE mode, if I am correct.

So what I would like to know first, why is the registry showing 3 instead of 0, and SHOULD it still be changed to 0, or left at setting 3, and secondly, if I were to install a SSD, would it work in this RAID selection mode (assuming it is AHCI also) .

By the way I did check in Command Prompt that the TRIM is activated (defaultdelete = 0).

Thanks for any advice or insight anyone might be able to give on this combination.
The computer is about 1.5 years old, so I figure it is FAIRLY up to date ... but these days .. even 6 months is almost obsolete ! :shock:

 

[WindowsStar]

You can change both "msahci = 0, and also the iaSTorV = 0" it will not hurt anything. If you are adding a new drive I would make sure both are set to zero. They maybe set to 3 because you are using another AHCI driver. RAID is the correct setting it will be RAID if you have one setup and AHCI if there is no RAID. -WS

Old thread.

 

[ZoltanGZ]

Thanks for your reply WindowStar. I will make the settings you suggested. ZGZ

 

[jetblst]

Wow Excellent tutorial. I am nervous around anything Registry, (I know back it up) but I am. This tutorial was spot on. Im going to put a link to it over at AVSIM. SSDs are getting some attention in the FSX community So far I love mine.

 

[Bare Foot Kid]

Hello jetblst, welcome to Seven Forums; pleased I could be a help!

 

[ROBO731]

My Value for start was already set to 0. So I can just change the setting in the bios right?

 

[TsunamiZ]

step 3 ... cilck "Exit"

note, the click is mispelled. great tutorial, though.