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Win7: Switched bios to AHCI and got a Blue Screen


Sep 25, 2001
Check this thread and follow the MS link as well.


I have also found this guide.


Overall you will not see much difference and if you do buy an SSD, go with a new installation setting your BIOS to AHCI first.
thx.. so no need to change it then with my current sata hard drive? leave it on IDE (or what ever the non-ahci option is in bios)?
wait till I get the SSD?


Golden Member
Mar 6, 2011
AHCI allows users to utilize advanced features that are available to SATA. The first feature is Native Command Queuing or NCQ. Without NCQ, each request is served sequentially without any optimization. NCQ analyzes the requests and rearranges them so that requested data locations that are physically closer to each other are grouped together so that they can be accessed in one pass and the time needed is minimized. AHCI also enables hot-plugging or the ability to attach or remove hard drives from a system that is running similar to a removable drive. This is not possible with IDE drives as they are configured during boot time.

Read more: Difference Between AHCI and IDE | Difference Between | AHCI vs IDE http://www.differencebetween.net/technology/difference-between-ahci-and-ide/#ixzz3JRekVbMS
NCQ and hotplug. Even with NCQ enabled you will not see much difference. But if you do get a new disk, enabling them will be better.


Sep 25, 2001
why does a ssd work more effieciently than sata w/ahci enabled?


Senior member
Mar 6, 2009
Try this:

Press Ctrl + X and select Command Prompt (A)dmin from the menu and then enter the following command:
bcdedit /set {current} safeboot minimal

Reboot and then enter the BIOS (typically press F1, F2, F10 or Delete)
Change the SATA drive setting to AHCI and exit the BIOS save settings.

Windows will boot into Safe Mode.

Open an Administrator Command Prompt again and enter the following command to disable Safe Mode boot:
bcdedit /deletevalue {current} safeboot

I have done this a couple of times and it worked great both times. :)

John Connor

Nov 30, 2012
You can't just turn on AHCI with a OS that was installed in IDE mode. You first need to do a system modification. Are you trying to do this with an OS that was installed in IDE mode?

Edit- Reading your thread you linked to it sounds like you have a fresh SSD that is causing a BSOD.

Make sure you also don't have two drives installed when you install Windows otherwise the BootMGR might get placed on the second drive.
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Golden Member
Nov 20, 2011
This thread got me interested in AHCI:

so I switched to ahci in bios and immediately got a BSOD.

I only have a single sata drive.
my mobo is a gigabyte ga-78LMT-sp2.

Whats wrong?
and how much better would my system run on AHCI?

For future reference; if the OS was installed in IDE mode and you would like to switch to AHCI mode just follow this simple five minute procedure:

1. Open regedit.
2. Go to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\services\msahci
3. Click on msahci, then in the right pane double-click the value Start.
4. Change the Start value data to 0, then click OK.
5. Go to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV
6. Click on IastorV, then in the right pane double-click the value Start.
7. Change the Start value data to 0, then click OK.
8. Close regedit, then shut down.
9. Restart the computer and immediately enter BIOS setup.
10. Find the SATA storage controller section and change the mode from IDE to AHCI.
11. Save settings and exit BIOS.

This procedure assumes IRST is installed but if not, just skip steps five, six and seven because there won't be a IastorV key in your registry. The msahci key is the critical key to edit. If Windows inadvertently gets booted without saving the IDE to AHCI change in BIOS, the entire procedure will need to be repeated from the beginning.

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Diamond Member
Nov 21, 2005
if you ever plan on re-installing the OS in the future -

you can try RT 7 Lite (64-bit), slip stream packaging for Windows 7 installations, works sometimes, not always perfect.

certain motherboard systems will freeze with enabling AHCI and SSD's w/Intel stroage controllers.

for fresh installs with default Microsoft-AHCI standard drivers, certain end-users have only a matter of a few minutes... before their systems BSOD or dysfunction before they can implement registry modifications to disable LPM and other tool-tricks.

the RT 7 Lite offers the option of installing the AHCI drivers (manufacturer storage controller) instead of using the default Windows 7 "standard AHCI" drivers which may be problematic for certain end-users.
the recommended approach if you're installing a new win7 OS would be to just install the manufacturer AHCI drivers before the OS finalizes versus trying to auto-inject the drivers as the OS installs on its own (which can cause OS errors because the RT 7 Lite software is beta/buggy).

"integration/unattended feature"
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