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

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• 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 atlcraig.



I'm glad you were able to get it sorted, thanks for the update.

 

[Everlong]

Just to put in here for nForce users, nForce boards do not support AHCI (with the exception of nForce boards that include onboard graphic cards), and also don't send the TRIM command for SSDs. It can do NCQ through its controller though. The JMicron SATA ports do support AHCI, but you'd get worse performance running a HDD through these, than on the normal SATA ports.

You can uninstall the Nvidia controller though in Device Manager and install Microsoft's IDE Controller, which can send TRIM commands for SSDs.

Head to Device Manager (Open Start menu, type Device Manager), and click "IDE ATA/ATAPI Controllers", and you will see 3 Nvidia Serial ATA Controllers. Right click one of them and click "Properties" and go to the "Driver" tab. Click "Update Driver". Click "Browse my Computer", and then "Let me pick". You will see the option to choose "Standard Dual Channel PCI IDE Controller". Click this and click "Next" and let it install.

Do the same for the other two Nvidia Controllers in Device Manager and restart your system. After the controllers have installed, you will be asked to reboot again.

SSDs will now have a slight performance boost with the TRIM command, and also regular HDDs also have a slight increase as well.


Feel free to add any of this to the first post, if you want Ted. Some nForce users might benefit from it.

 

[Bare Foot Kid]

Thanks EL, as you know the info has been added to the first post after the tutorial.

I just made this post so others will know of it.

 

[ZaLiTH]

I've used this process before on my PC, switching to AHCI gave me a pretty decent performance boost... I find it's more helpful for maintaining the speed of a computer though. As data on a drive becomes more fragmented, it doesn't affect your PC speed quite as much as the standard SATA mode.

I have a question though, I want to configure two spare 80GB SATA drives I have in RAID0 to see how they perform... Should I use this same process beforehand to get Windows to reinstall the drivers? I would think so, simply based on the principle behind this is to get Windows to redo drivers... But I'm not sure due to the key being named 'msahci'. Anybody care to clear that up for me?

Edit: Just to explain why I'm asking this, I'm going to Ghost my C:\ and restore the image onto my RAIDed 80GBs, that way I don't need to reinstall everything from scratch... If this process is an option, I'll end up making the registry change before Ghosting my C:\ partition, that way when Windows starts up with my drives in RAID mode it'll attempt to reinstall drivers on that boot.

 

[Bare Foot Kid]

Hello ZaLiTH.



In my BIOS I have the option for AHCI or RAID, not both, I'm sure it'll be the same way for yours; you would need to change it to RAID before OS installation.

Did I misunderstand your question?

 

[swarfega]

When I changed HDs recently I switched to ahci because I wasnt raiding them. I feel it is slower.

 

[ZaLiTH]

Hello ZaLiTH.



In my BIOS I have the option for AHCI or RAID, not both, I'm sure it'll be the same way for yours; you would need to change it to RAID before OS installation.

Did I misunderstand your question?

Yeah, think you did a little bit there... I know it's AHCI or RAID, which is why I said:

I want to configure two spare 80GB SATA drives I have in RAID0 to see how they perform...

The only reason I'm asking here, is regarding the drive controller drivers that my Windows installation currently has (for the AHCI configuration). When I first installed, it was straight SATA mode, then I used this tutorial to switch to AHCI mode, now I'm asking if the same process can be used to switch from AHCI to RAID.

This tutorial would be used to get an already installed copy of Windows to reinstall the drive controller drivers, right? So, by my logic; I would (1) change the registry setting as mentioned, (2) make a Ghost image of my C:\ with Windows and put it on an external HDD, (3) shut down and install my two 80GB drives in RAID0, then (4) restore the Ghost image onto a partition created on my RAID0 array.

Well, let's put it this way, I'm not going to delete the partition with Windows on my 400GB until I know it's working properly with a RAID setup, so I'll try it this weekend regardless and then let you all know how it went on Monday.

When I changed HDs recently I switched to ahci because I wasnt raiding them. I feel it is slower.

You mean AHCI was slower? Well, if you were comparing it to RAID0 or RAID5 (with a decent controller), then yeah, it would be slower than RAID..

 

[Bare Foot Kid]

I want to configure two spare 80GB SATA drives I have in RAID0 to see how they perform...

Hello again.


I thought so, as I have no experience with RAID I'm no help for an answer but I'm curious to know the outcome so please post back to tell how it sorts out.

 

[ZaLiTH]

I want to configure two spare 80GB SATA drives I have in RAID0 to see how they perform...

Hello again.


I thought so, as I have no experience with RAID I'm no help for an answer but I'm curious to know the outcome so please post back to tell how it sorts out.

Definitely, I will.. I'll be changing my setup over the weekend, so that gives me time to figure out the finer details and do some "before and after" benchmarks. I'll post the results of that in the performance sub-forum on Monday.

 

[LM2008]

mine shows 3, should i change it to 0? strange thing is that my laptop has the AHCI option in the bios, but windows or the registry shows "3"

 

[Bare Foot Kid]

mine shows 3, should i change it to 0? strange thing is that my laptop has the AHCI option in the bios, but windows or the registry shows "3"

Hello LM2008.



Yes, starting at step #3 and finish what the tutorial says to do.

 

[LM2008]

no AHCI drivers message appeared or asking to restart, is there anyway to verify is active?

 

[Bare Foot Kid]

no AHCI drivers message appeared or asking to restart, is there anyway to verify is active?

Howdy.


After you changed the registry value in step #3 did you re-start the PC and change it to "AHCI" like in step #4 below?

4)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.

 

[LM2008]

yes

 

[atlcraig]

AHCI Performance

Just an update of what I found out about ahci performance! After I installed and got ahci working I checked for any performance change in Windows 7 hard drives. My drive performance before I changed to ahci was 5.4 and after the change it was still 5.4. I then installed a SSD as my C drive and my drive performance went from 5.4 to 7.1! If I would have known this before I started I don't think I would have changed to ahci. So my advice to anyone wanting to increase the drive performance on their system would be to go out and buy a SSD.

 

[Dave76]

The WEI is not a good benchmark.

If you what a more accurate benchmark use HD Tune or Crystal Disk.

AS SSD Benchmark is a good one for SSDs.

It will also depend on the specs of the HDD and SSD. An older SATA drive may not be able to directly use some of the benefits.
A WEI of 5.4 tells me it may be an older model or have other issues. A 'Green' version uses less power and has less performance.
For the best performance get a 7200 RPM, 32 MB cache, HDD. Be sure it is SATA 2 and supports NCQ, S.M.A.R.T. and Plug and Play.

There're other benefits like NCQ Native Command Queuing, will get the data faster with less wear on the HD. Plug and Play, if you need it, ie external HD. As mentioned earlier.

The best benefit with a SSD is AHCI will enable Trim when using win7.

Some SSDs will seem to have better specs but will get lower benchmarks and WEI score due to the I/O rates.

 

[ZaLiTH]

Definitely, I will.. I'll be changing my setup over the weekend, so that gives me time to figure out the finer details and do some "before and after" benchmarks. I'll post the results of that in the performance sub-forum on Monday.

And here I am quoting myself, yet again... Lol.

Anyway, I ran into a few issues with trying to switch to RAID; my BIOS won't allow me to change my boot order when RAID is enabled... Everytime I try set my DVD drive as first boot device, when I go back into my BIOS my RAID array is back at the top of the list. I figure it's either an issue with my DVD-RW using a SATA interface, my BIOS version (1.6), or in the worst case my physical BIOS chip.. Hopefully a BIOS flash to 1.7 will sort it out, I'll see tonight.

 

[atlcraig]

Dave76

Thanks for the information, I will try the other benchmark tools you listed and see what kind of score. I have four SATA drives on my system of different ages so that may be causing the low scores.

 

[Dave76]

Your welcome, run the benchmarks on the HDDs and post them on the Show us your hard drive performance thread.

And your SSD on the Show us your SSD performance thread.

You might see some performance improvement by moving your OS to the fastest HDD, or obviously to the SSD, if your running only one OS.

 

[Gu1air]

Thank you so much for this info. After getting a Sata Dvd-Rw I was having a lot of buffer problems and I noticed that my bios was set to IDE. I changed to AHCI and Windows7 said it could not boot

I had to change back to IDE. This allowed me to boot back to windiows and checked this forum for any solution. There was my life saver information. I quickly followed this tutorial and my windows was back up and running.

Excellent info. Keep up the good work.