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

 

[Golden]

I'm not entirely sure case. I didn't bother mucking with mine, and its running sweet as.

 

[Dave76]

HI Case,

I'm not sure about the trim stuff, but here is a link that will give you some additional tips to keeping your SSD nice and clean:

Guide * Windows 7 Ultimate Tweaks & Utilities *

Regards,
Golden

Hi Golden,

I checked and it shows that TRIM is enabled. Is TRIM something that works automatically or do I manually have to do it?

Case and Golden,
Some of the tweaks given at many SSD sites are for Gen1 SSDs and my not be needed for Gen2 SSDs.

Here is an OCZ thread dated after the thread you linked talking about this issue.

Just what tweaks are needed in win7 with SSD?

This thread is not a definitive list of what MUST be tweaked, it is simply a discussion of what various users have tweaked and had good results with.


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..
.... (Edited)
#9 The tweaks:

Disable Superfetch

Disable Defrag scheduler

Disable drive Indexing

I set the power state to high performance and set the machine to never sleep, HDD power down to OFF but I do set the screen to go off after 1hr.

I rarely touch pagefile when testing drives, I let the pagefile be on the SSD. I also leave Hibernate alone and also system restore is left alone.


So, you should see I do very little, I have worked on tweaks BUT I believe they are more aimed at the enthusiast and not the day to day user.

So...lets discuss what we think is best for just day to day easy to implement tweaks. I think what I do here is all that is needed...what do you all think?

Edit:

I just read a post from Praz explaining something I had not noticed. People now think you have to tweak windows with OCZ SSD, the fact is you do not.

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.

Be aware...I am not saying do not tweak the system if you wish, what I am saying is most think you HAVE TO tweak the system....fact is you do not.

As mentioned, if you want to change settings and experiment, tweak and/or play with the settings, by all means do it.

The above quote just says that it's not required and may not give you any noticeable improvements.
It's up to you if you want to do most of these tweaks.


Case, the easy way to check your firmware is to D/L AS SSD, you don't have to run it, in the upper left corner just under 'Intel' will be the firm ware version.

Intel Download Center for the X25-V

Intel SATA Solid-State Drive Firmware Update Tool

Intel SATA Solid-State Drive Firmware Update Tool FAQ
​

 

[MaxKohler]

Nice tutorial. Rep upped.

Just one quick question - are there any general performance hits or gains from this?

Not sure if someone said this already in one of the 31 pages, but the performance increase is very noticeable. When moving files around 1.5GB it would start around 46MB/s and slow down more and more till the end it was about 18MB/s. Now with AHCI enabled it starts around 60MB/s and doesn't go below 33MB/s even with much larger files. So it's almost twice as fast...

 

[ZaLiTH]

Nice tutorial. Rep upped.

Just one quick question - are there any general performance hits or gains from this?

Not sure if someone said this already in one of the 31 pages, but the performance increase is very noticeable. When moving files around 1.5GB it would start around 46MB/s and slow down more and more till the end it was about 18MB/s. Now with AHCI enabled it starts around 60MB/s and doesn't go below 33MB/s even with much larger files. So it's almost twice as fast...

I think a few people have mentioned things like this here and there (including me), but it seems you'll get a more noticeable performance gain if you have a drive that's had any fragmentation on it. The NCQ features of AHCI / RAID help a lot with reading (and I assume writing) to fragmented drives.

I have a theory that even a drive that was fragmented at some point and now no longer is can see a performance boost... The defrag process simply file fragments so each individual file is either not or at least less fragmented. But that doesn't necessarily mean that all the files in a folder are in one section of the drive platter.

By that, NCQ will help with reading a series of files that are on different areas of the drive platter more efficiently. Then again, that is just a theory and I may be horribly wrong, it's just my opinion.

For whatever reason, AHCI can help boost access speeds of almost any decent drive.

 

[Bare Foot Kid]

Well said!

 

[Dave76]

Agree with both of you

 

[ZaLiTH]

Well said!

Agree with both of you

Hehe... Thanks guys.

 

[Golden]

Hi,

For those of you have turned OFF disk indexing on your SSD's like me, be aware that I have run into problems with arranging files in Libraries because of this.

So, if you make extensive use of Libraries and you have an SSD, you may want to reconsider turning off indexing, or coming up with an alternate strategy. I'm still trying to work out what to do.....

Here is a link to my original post about this - rep to Brink for confirming the issue:

http://www.sevenforums.com/general-discussion/140939-library-question.html

Regards,
Golden

 

[ZaLiTH]

Hi,

For those of you have turned OFF disk indexing on your SSD's like me, be aware that I have run into problems with arranging files in Libraries because of this.

So, if you make extensive use of Libraries and you have an SSD, you may want to reconsider turning off indexing, or coming up with an alternate strategy. I'm still trying to work out what to do.....

Here is a link to my original post about this - rep to Brink for confirming the issue:

http://www.sevenforums.com/general-discussion/140939-library-question.html

Regards,
Golden

I'd hazard a guess that the issue you described would probably affect normal drive users as well... Disabling File Indexing would affect how Windows handles the files themselves, it makes sense with the libraries if you think about it; a library in Win7 is essentially a dynamic folder, so sorting data in that dynamic folder without having indexed information on hand would be pretty impractical. If MS did still allow it, it would be dog slow and definitely not worth doing.

I also use the libraries a hell of a lot on my PC, mostly because I've got too much Anime / Movies / Series to fit all into one folder, so I use libraries to make it easier to make my "Media", "Data" and "Install Files" folders easier to find and use.


Hmmm....

I'd better stop there before I start going off-topic with crap like folder sharing with libraries. Lol.

 

[Golden]

Hey Zalith : is that on an SSD out of interest?

 

[ZaLiTH]

Hey Zalith : is that on an SSD out of interest?

I don't own one (yeah yeah, laugh... I don't need one... [1]), so I can only post my opinion on normal old-school spinners. Honestly though, since 'Indexing' in Windows is a cache of file info (creation date, modify date, file size, file name, etc.) I think that having Indexing disabled would give the same results on a PC regardless of the drive type..

I tried disabling Indexing on my PC ages back to see if it made any difference in performance, and the performance I gained in gaming (more resources available for the game) wasn't enough to justify the performance lost in the straight drive access department through 'Computer'. So I left it enabled. That was before I started using the libraries though, so I am just speculating here...

Anyways, I'm leaving work now (still no 'net at home.. *sob sob*), so I won't see any replies until tomorrow.


[1] - I keep telling myself that anyway... Just to make myself feel better. Lol.

 

[seekermeister]

I will admit that I only read the first page of this thread, so my question may have been answered later, but to prevent any confusion, I will simply ask my own question. I have an A8N32-SLI Deluxe motherboard, which has an nForce 4 chipset. I currently have the BIOS set for non-RAID. If I understood correctly, this would need to be changed to RAID, to enable ACHI. I read some caveats, which I will need to sort through more carefully, but before doing so, I need to know if I should change this to ACHI in the first place? Since this changes the way that data is handled, what would happen with the structure of data on the hard drive that already exists? Would changing to this mode of operation be safe for my computer?

EDIT: All of my drives are hard drives, no SSDs involved.

 

[Bare Foot Kid]

I will admit that I only read the first page of this thread, so my question may have been answered later, but to prevent any confusion, I will simply ask my own question. I have an A8N32-SLI Deluxe motherboard, which has an nForce 4 chipset. I currently have the BIOS set for non-RAID. If I understood correctly, this would need to be changed to RAID, to enable ACHI. I read some caveats, which I will need to sort through more carefully, but before doing so, I need to know if I should change this to ACHI in the first place? Since this changes the way that data is handled, what would happen with the structure of data on the hard drive that already exists? Would changing to this mode of operation be safe for my computer?

EDIT: All of my drives are hard drives, no SSDs involved.

Have you had a look at the info from Everlong about nForce boards?

 

[seekermeister]

I'm not sure what I'm supposed to do with that link, since it only take me to his profile?

 

[Bare Foot Kid]

I'm not sure what I'm supposed to do with that link, since it only take me to his profile?

I was referring to the information he posted in the first post after the main body of this tutorial, sorry for not being clear.

 

[seekermeister]

I'm still lost. I scrolled down through the entire first page of this thread, and didn't find him anywhere. How about a permalink?

 

[Bare Foot Kid]

I'm still lost. I scrolled down through the entire first page of this thread, and didn't find him anywhere. How about a permalink?

http://www.sevenforums.com/711504-post1.html

 

[seekermeister]

Now I see why I didn't find it, I was looking for a post made by Everlong, rather than one by you giving him credit. I am not sure, but I have read that AHCI can be enabled, by selecting the RAID option in the BIOS, but not setting up an array. Even with an array setup, any drive outside of that array will still have AHCI enabled. I can't be positive that included nForce 4 boards, because what I read wasn't specific, but I tend to think that it did.

I got the impression that most of Everlong's method was designed to accommodate SSDs, which I don't have. It sounds as though you don't know about nForce 4 yourself, but maybe someone does?

 

[Bare Foot Kid]

I know nothing about nForce and never said I did, that's why the reference to Everlongs' info.

 

[seekermeister]

Yes, I understood that from the beginning. If I gave the impression otherwise, I apologize. I may have been wrong about what I said about enabling AHCI using the RAID setting, because I just went through the Asus FAQ and found nothing about it regarding my motherboard. Perhaps what I read was only for others.