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

 

[Mulaka]

That's just it guys, I have the latest nVidia drivers installed, and it still shows up like the screenshot.

 

[Buggsy2]

OCZ says do not activate AHCI

OCZ Technology says not to activate AHCI:

AHCI
AHCI is not official supported on OCZ SSDs and may under some circumstances affect performance, specifically during windows installation. Enabling AHCI can result in higher performance in synthetic benchmarks for SSDs and HDDs alike, but can cause hang-ups and intermittent freezes in SSDs since it allows multiple access requests to compete for a drive that is not made to address re-ordering of commands in the queue. We recommend AHCI is set to disabled in both Windows and in the BIOS.
Native Command Queuing greatly increases the performance of standard rotational drives but it has no bearing on SSDs.

 

[Bare Foot Kid]

OCZ Technology says not to activate AHCI:

AHCI
AHCI is not official supported on OCZ SSDs and may under some circumstances affect performance, specifically during windows installation. Enabling AHCI can result in higher performance in synthetic benchmarks for SSDs and HDDs alike, but can cause hang-ups and intermittent freezes in SSDs since it allows multiple access requests to compete for a drive that is not made to address re-ordering of commands in the queue. We recommend AHCI is set to disabled in both Windows and in the BIOS.
Native Command Queuing greatly increases the performance of standard rotational drives but it has no bearing on SSDs.

They should get Intel then eh, I've been using my Intel X25 M 80GB G2 for about 10 months and haven't had one single issue; I couldn't count the number of re-installs (with 'clean all' - secure erase) I've done while working on this.


SSD / HDD : Optimize for Windows Reinstallation



Thanks for taking time to post the info though.

 

[Dave76]

OCZ says USE AHCI for BETTER performance

OCZ Technology says not to activate AHCI:

AHCI
AHCI is not official supported on OCZ SSDs and may under some circumstances affect performance, specifically during windows installation. Enabling AHCI can result in higher performance in synthetic benchmarks for SSDs and HDDs alike, but can cause hang-ups and intermittent freezes in SSDs since it allows multiple access requests to compete for a drive that is not made to address re-ordering of commands in the queue. We recommend AHCI is set to disabled in both Windows and in the BIOS.
Native Command Queuing greatly increases the performance of standard rotational drives but it has no bearing on SSDs.

The address "res_old" makes me wonder just how old this article is.

Can you post the address that it originated from?

This is for early editions of their SSDs.

Edit:
From the OCZ support site,
If using an Intel chipset based system please use the newest Intel chipset drivers for Vertex LE, vertex2 and Agility2

For now its important you use the Intel chipset driver for ahci mode.

This is for the gen2 versions, with FW updates AHCI should be the best way to go on all OCZ SSDs.

And this from 'Official Staff':

I see arguments and conflicting advice...so lets settle the debate here in this thread before i write a new guide.

At this time when I test a system i do the following tweaks and NOTHING ELSE..

1) I check the board is in AHCI mode, if no option is available there is nothing you can do.

... (see the link for more)

The SSD forum here has got cross saturation from the gen1 forum where tweaks were needed. Vertex, Agility, Turbo and Summit are all what we call Gen2 and do not need tweaking at all. On the most part win7 in AHCI mode will do all the tweak you need for single disk operation all by its self...it looks like people on the whole have forgotten that part.

Please, take care to post accurate information, we don't want to give the wrong guidance to other viewers.

 

[dengland]

Thanks ! Just what I needed.

 

[Bare Foot Kid]

Hello dengland, welcome to Seven Forums; glad we could be a help.

 

[bearcave]

Hey All,

First off my system:
Motherboard: Asus P7P55D Pro
CPU: Core i7 2.8ghz
Video Card: ATI 5850
Ram 8gb DDR3
HDD: 500gb Sata II
OS: Windows 7 Pro 64bit

My problem.

I followed the tutorial, went into the registry, and tried to edit the value of msachi and noticed that start was already set to 0. I then went into bio and set it to ACHI mode. Upon reboot the computer got to the nice little windows 7 orbs that form the logo and then rebooted. I switched back to IDE, returned to windows figuring I had to download the drivers.

I went to the Asus site and found the Intel Sata drivers. When I tried to install them it said "you do not meet the minimum system requirements" I then went to the intel site and downloaded their "Matrix Storage manager" and "Rapid Storage Technologies" Upon trying to install each of these I got the same "minimum system requirements error".

At this point I am out of ideas, and would value any suggestions.

 

[Bare Foot Kid]

Hello bearcave, welcome to Seven Forums!





If the value in the registry was at ' 0 ' to start with, AHCI was already enabled in Windows.

 

[bearcave]

Hello bearcave, welcome to Seven Forums!





If the value in the registry was at ' 0 ' to start with, AHCI was already enabled in Windows.

That's what I had figured,

but why then would it just continually reboot when I set it to AHCI mode in the bios?

 

[Bare Foot Kid]

Hello bearcave, welcome to Seven Forums!





If the value in the registry was at ' 0 ' to start with, AHCI was already enabled in Windows.

That's what I had figured,

but why then would it just continually reboot when I set it to AHCI mode in the bios?

Something is out of order, if it's not/wasn't set in the BIOS to AHCI, Windows automatically disables the AHCI drivers during OS install.
Do you have a lot of data to lose if you re-install; just asking.



These are the wrong ones, as far as I know; I haven't used this technology.

Matrix Storage manager" and "Rapid Storage Technologies"

 

[bearcave]

Hello bearcave, welcome to Seven Forums!





If the value in the registry was at ' 0 ' to start with, AHCI was already enabled in Windows.

That's what I had figured,

but why then would it just continually reboot when I set it to AHCI mode in the bios?

Something is out of order, if it's not/wasn't set in the BIOS to AHCI, Windows automatically disables the AHCI drivers during OS install.
Do you have a lot of data to lose if you re-install; just asking.



These are the wrong ones, as far as I know; I haven't used this technology.

Matrix Storage manager" and "Rapid Storage Technologies"

Not data loss, all of my data is on a separate partition and everything "music" "documents" just point to that partition and I have the data backed up. It's more the many hours of reinstalling all of my programs and then tweaking things to the way I like them.

I wonder if I went into the registry, disabled the msachi start=3 rebooted and then went it and re-enabled it would that make any difference? or is there something I can do to the hdd drivers that would change them to AHCI mode?

 

[Bare Foot Kid]

Can you get to the registry to change the value to find out, at this point, it can't hurt right?

 

[bearcave]

Can you get to the registry to change the value to find out, at this point, it can't hurt right?

Well i tired it, I went into the registry changed the start value of msachi to 3 rebooted, went back in changed it to 0 shutdown, went into bios enabled achi, and started up. No joy!! I also took off the auto restart and got the standard stop code 0x0000007b.

This is all of the values for msahci in my registry
(default) = value not set
driverpackageid = mshdc.inf_amd64_neutral_a69a58a4286f0b22
errorcontrol = 0x0000003 (3)
group = scsi miniport
imagepath = system32\drivers\msahci.sys
start = 0x000000 (0)
tag = 0x0000040 (64)
type = 0x0000001(1)

There is a sub-folder called Enum
default = value not set
0 = root\legacy_msahci\000
count = 0x0000001 (1)
nextinstance 0x0000001 (1)

I noticed that the driverpackageid says amd64, and i'm running an intel system could this have something to do with it? I have the wrong drivers?

 

[Bare Foot Kid]

Sorry mate, I'm at the limit of my knowledge here and I have no further suggestions but just for conversation sake, here's a snip of my "Enum" sub-folder, different than yours.



click to enlarge

 

[bearcave]

Sorry mate, I'm at the limit of my knowledge here and I have no further suggestions but just for conversation sake, here's a snip of my "Enum" sub-folder, different than yours.


click to enlarge
View attachment 88991

No worries, I'm at the limit of mine as well. Interesting difference though. is your msachi folder significantly different than mine?

 

[Bare Foot Kid]

Exactaly the same.

 

[bearcave]

So I ended up breaking down and doing a fresh install with AHCI selected in the bios. I works great. Thanks for all your help.

Funny thing is I did this so I can install Snow Leopard on my other 500gb and dual boot it with windows 7. But I still haven't been able to get snow leopard to install .

Something else to figure out I guess

Thanks again for your help.

 

[Bare Foot Kid]

So I ended up breaking down and doing a fresh install with AHCI selected in the bios. I works great. Thanks for all your help.

Funny thing is I did this so I can install Snow Leopard on my other 500gb and dual boot it with windows 7. But I still haven't been able to get snow leopard to install .

Something else to figure out I guess

Thanks again for your help.

Thank you and thanks for the update.

 

[bagavan]

I have a normal HDD will there be any performance improvements?

 

[ZaLiTH]

I have a normal HDD will there be any performance improvements?

AHCI is a SATA feature, so when you say a 'normal drive', does it use the SATA (Serial ATA - Wikipedia, the free encyclopedia) or IDE (Parallel ATA - Wikipedia, the free encyclopedia) interface to connect to your motherboard?

If it uses SATA you can use it and may notice an improvement, if it uses IDE then you won't be able to make use of this feature.