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

 

[Brink]

Chamjiee,

I'm afraid that I do not have enough experience with Windows Server 2012 R2 to better help.

Personally, I'd change it back to what you had before to avoid it rebooting. Otherwise, you may need to reinstall Windows Server 2012 R2 with AHCI selected in BIOS first to have it AHCI.

I think I will have to do so. Until then hope op mentions these caveats

Well, the tutorial was not written for Windows Server 2012 R2 though.

 

[chamjiee]

Well, the tutorial was not written for Windows Server 2012 R2 though.

Ya one could be dual booting it with windows 7 like me. So at least a warning that if you are dual booting with server 2012r2 then be warned..

 

[Paulista]

Hi.
I´m sorry, but I haven´t read all pages.
But I do follow yours instructions and I appreciate a lot.

Unfortutetly, I haven´t had success and my computer keeps rebooting and blinking a bluescreen impossible to read.
I found a page from Microsoft that solve my problem:
Error message occurs after you change the SATA mode of the boot drive
Modifying two registry keys instead of only one:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV

from "3" to "0"

I just want to share this in a forum that already helped me so many times.

Thanks guys,

 

[Brink]

Thank you Paulista, and welcome to Seven Forums.

The tutorial has been updated to include this.

 

[DocDJ]

Brink,
You might also note that the choice of whether to use MSAHCI vs. IAStor is not clear-cut. Since I changed it to install a Samsung SSD with an Apricorn Solo X2, I used MSAHCI. Some folks say that the Intel driver is better (but they don't say how well it works with non-Intel drives, if at all).

PS. The Solo X2 took my boot-drive sequential write speed from 68 to 507 MB/s. I was using a 7200 RPM drive. Read speed went up to 523 MB/s. Random reads went up to 47571 MB/s. I use it ONLY for my system files and user/appdata, but NOT My Documents/Pictures/Music (moved them to another HD drive).

 

[general714]

For those generally having issues, I thought that I'd briefly describe my situation.

I've had issues with the computer freezing and the cursor changing. Freezes for a few seconds then goes back, then increasing in frequency then usually I have to reboot which cures it for a hour or so.

It was something to do with my SATA configuration. Tried everything, including advice in this thread, but what finally resolved it was installing the Intel Rapid Storage Technology enterprise software (best to Google it as I downloaded it via the Dell website).

Once installed, I rebooted and finally my system installed the correct drivers for both my hard drives and I've had no issues since.

Best of Luck!

 

[Redwald]

Thanks to Barefoot Kid for originally posting this thread more than 3 years ago and to Brink and all who have helped afterwards. Glad its still alive.

I just recently made the switch to AHCI after forgetting to reset my bios after a reinstall of Win 7 a couple of weeks ago. All went well or so it seems.

I only have one sata2 wd 500gb HDD and one sata DVD drive.
The bios screen now shows that the AHCI bios driver is loading and finding devices. So thats good. But in the windows Device Manager. I have a couple of yellow ! marks on some of the ATA channels. If I look at their properties it says "This device cannot start. (Code 10)" (see picture).



What concerns me is that there are 5 channel 0's, 5 channel 1's, 2 channel 2's, etc. Why so many channels? Why is the yellow! sign only on two of them?
I know why there's a yellow ! sign next to the Marvel 91xx device. Its because I don't have a RAID and never installed a device driver for that controller.

Here is a pic of my Gigabyte MB page with the SATA connector layout.




My computer seems to work fine, but why the yellow !'s?

Maybe after going to AHCI I need to install the Marvell drivers even tho I'm not using those connectors?

I'm stumped... any thoughts would be appreciated.

 

[WindowsStar]

Fixing the Marvell driver will probably fix the other yellow ! errors.

 

[kalpik]

I followed this tutorial, and the microsoft fixit, but I'm still getting a BSOD on start if I switch to AHCI. Boots fine in IDE mode. Any other thing I need to take care of?

 

[Brink]

Hello Kalpik, and welcome to Seven Forums.

Sorry, but I have to ask to verify. Is this for a SATA hard drive?

If so, do you have the latest BIOS firmware version on your motherboard?

 

[kalpik]

Hello Kalpik, and welcome to Seven Forums.

Sorry, but I have to ask to verify. Is this for a SATA hard drive?

If so, do you have the latest BIOS firmware version on your motherboard?

Hi Brink!

Thanks for your reply! I solved it myself by enabling iaStor too (not iaStorV). Now it boots fine

 

[Brink]

Great news.

 

[metalbunny]

Just registered to say thanks for this tutorial. Wasn't aware that NCQ depended on controller mode until today.

Been trying to get my 2 TB Seagate 7200.14 to act normally (folks, don't buy Seagate 7200.14 or 7200.15 drives, they're garbage), and was hoping maybe turning on the NCQ would help somewhat with the performance drain that drive has on the system. Haven't had a chance to find out if it helps yet, but my boot drive is a WD Black which was built for NCQ operation, so either way I want NCQ on.

For those unaware: The problem with the Seagate 7200.14 (aka Barracuda V) and 7200.15 drives is the firmware. It's written to discourage using them in RAID setups, so it fakes death by sending fake HALT commands to the controller now and then, which causes all kinds of problems. Seagate won't admit to this behaviour, but command logs show the proof. I've flashed the drive's firmware, which has resulted in the drive merely stalling the system when it has to go through a hard reset, instead of before where it would lock up and disappear from the system, causing all kinds of wonderful errors.
If your drive controller is not RAID capable you supposedly won't have any issues whatsoever with these drives. If, however, your controller IS RAID capable (which most high performance computers are), then the controller will go into a panic whenever the drive sends those fake death notices. Only solution is to not use those drives with RAID-capable controllers (whether running RAID or not), but sadly I can't afford to replace it with a nice WD yet, since 2 TB drives are still a tad expensive.

EDIT: Had a driver crash (buffer overflow) which led to more "fun" Windows stupidity, which led to me reinstalling... now Windows flat out refuses to use the correct SATA driver, and as far as I can tell, refuses to even run in AHCI mode. Redid the registry as before, deleted the device in device manager, rebooted. I still get "AMD SATA controller" and "Standard Dual Channel PCI IDE controller". Attempting to force update the driver fails, Windows insists it's using the right one.

EDIT 2: Switched the BIOS back to "IDE", which gave me 3 dual channel controllers in device manager and 6 ATA channels listed. Then rebooted and switched to "AHCI" once again. Now I'm back to having it listed as "Standard Dual Channel" and only 2 ATA channels are listed. I still have access to all my drives, but it's still stuck on the MS drivers, and seems no matter how many times I reinstall the AMD driver it will not use it. Wtf gives with that? Makes no sense.

EDIT 3: Appears I had forgotten to install the E-SATA driver. Now I've got AMD SATA controller under IDE ATA/ATAPI controllers, and JMicron under Storage controllers. No other drive controllers listed. For some reason I can't find the E-sata in the BIOS to disable it. Everything else is listed but that.

 

[bibhu60]

Please help

Really great tutorial..
I am running windows 8.1 with windows 7 and I want to enable AHCI .
I am thinking that if I enable AIHC in windows 8.1 and reboot and set AHCI in Bios also then I will not be able to boot into windows 7.
So can you please tell what to do in order to boot both operating system in AHCI mode..
TIA.

 

[Brink]

Hello Bibhu, and welcome to Seven Forums.

That would be correct. You would need to do steps 1 to 6 in the tutorial in both Windows 8.1 and Windows 7 first, then restart to BIOS to finish.

 

[dancinbear]

I did as you suggested and when all is said and done, all I get is a non-flashing cursor in the top left quadrant of the screen right before Windows should load. My choices are sata 1-4: ide, raid, achi. If I choose achi, it won't load. I have an Asus M4A89GTD Pro/USB3. I hope I have given enough information.

 

[DocDJ]

I don't know which post you are referring to, but you MUST change to AHCI in Windows, and re-boot, BEFORE you shutdown (again) and go into BIOS turn it on there. Your SSD should not be installed until AFTER you successfully get the AHCI changed in BIOS. There are TWO registry keys for setting AHCI. you only need to set ONE of them. I used this one: HKEY_LOCAL_MACHINE\System\CurrentControlSet\services\msahci
I am using an Apricorn SOLO X2 PCIE2 adapter+Samsung 840 PRO 256GB drive.

 

[dancinbear]

Thanks, DocDJ. I apologize for the confusion-story of my life. I just kept plugging along. The key for me was changing iaStorV to zero. I thought I had already done it, so I didn't check it again. I went back and it was at "3" again. Changed it to zero as well, went through the routine and all is well. Thanks so much for your help.

 

[DocDJ]

Dancinbear: you're welcome. I used the windows default key because it is supposed to work for all SSD's.

 

[looked]

Hello to everyone and thanks for great forums. First post although I always visited the news around here. I don't remember what procedure I followed when I installed Windows but I hope I did it right. I see from my Device Manager window that drives are displayed as ATA and this makes me so confused. I took a screenshot showing the hard drives but I was not able to attach to my replay, could you please give me any advice? Thanks in advance.