How to Switch from IDE to AHCI without repairing/reinstalling windows

By +Warwagon
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Grand Master

+Warwagon MVC

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About 2 months ago I installed an SSD drive in my media center. For some reason up until tonight I never checked what the Sata mode was set to in the bios. It was set to IDE. I also really wasn't keen in reinstalling windows. Of course once you change it in the bios from IDE to AHCI windows will no longer boot. So I looked around the internet and found some really great instruction to switch from IDE to AHCI without having to repair or reinstall windows.

You start with step 1 while you are still in windows in IDE mode.

1) Run the Registry Editor (regedit.exe)

2) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci

3) Set the "Start" value to 0 (zero)

4) Navigate to Registry Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Pciide

5) Set the "Start" value to 0 (zero)

6) Shut down

7) Start up again, but before Windows boots go into the BIOS configuration screens and change the disk mode to "AHCI". Save the new BIOS configuration and restart so that Windows boots.

When Windows starts, it will detect the change, load new disk drivers, and do one more reboot to start up with them.

Veteran

neo158

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I had to do this with my install as the new mobo had AHCI enabled by default.

Also, this trick only works on Windows Vista/7.

Microsoft have a Fix-It for this, it's linked in my sig.

Grand Master

+Warwagon MVC

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I had to do this with my install as the new mobo had AHCI enabled by default.

Also, this trick only works on Windows Vista/7.

Microsoft have a Fix-It for this, it's linked in my sig.

Thanks for the head up. Title edited

Grand Master

+Warwagon MVC

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Is there any real world benefit for using AHCI instead of IDE if i'm not running raid?

Apparently AHCI gives you much better performance when using SSD drives (but don't quote me on that)

Grand Master

Draconian Guppy

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checked neo158's sig and came up with:

AHCI provides several features for SATA devices. These include hot plug functionality and power management functionality. For more information about the AHCI specification, visit the following Intel Web site:

http://www.intel.com/technology/serialata/ahci.htm

No really worth it I guess, at least not for HDDs not paired in any raid.

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iron2000

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Msahci is already set to 3 and pciide is already set to 0, I assume this is running in AHCI mode already, right?

Maybe you can check in Device Manager under "IDE ATA/ATAPI controllers", if you're on AHCI there should be an AHCI controller under it.

To add on, if you don't like your internal drives showing up in "safely remove hardware" in the task tray - heres a tweak:

http://www.overclock.net/raid-controllers-software/974023-fix-ahci-sata-drives-showing-safely.html

----

Just tried AHCI on my P5K SE yesterday.

Had to flash a modded BIOS to unlock it.

Found the HDD connected to the first and second to SATA ports on the mb stuck at Multi-word DMA mode 2 (read from Device Manager).

Disk Management was also not working, it keeps on loading for a long time with a blank window.

In the end switched back to good old IDE where all drives are at UDMA mode 5 (though according to HDtune, my drives are capable of more.)

But everything works.

Grand Master

kinetix63 Veteran

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Is there any real world benefit for using AHCI instead of IDE if i'm not running raid?

Yes... provided you've got a hard drive that supports it (and most SATA-II drives do), AHCI enables Native Command Queuing on the drive, which can increase drive life and make things a bit faster. Of course, this doesn't really apply to SSD's, but for standard drives it's a big benefit: http://en.wikipedia.org/wiki/Native_command_queuing

  • 1 month later...
Grand Master

Steven P. Administrators

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This trick won't work with a NT5-OS right?

2K/XP supposedly supports it, you might want to read up on it though: http://www.overclock.net/intel-motherboards/269993-how-enable-ahci-ncq-windows-2k.html

  • 4 months later...
Apprentice

kevpc

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hi all. would like some advice before i try the guide, if possible.

just got a new, overclocked system. mobo is Gigabyte Z68XP-UD4, running an i5 2500k o/c to 4.6gHz, 8gig DDR3 1600mhz Ram, nVidia GTX 550TI 1 Meg graphics card, WD Black Caviar 500gig sata lll hdd connected to sata lll on mobo. SATA ll Pioneer DVD Burner on a SATA ll connector and Pioner Sata BluRay burner on SATA ll connector,

i didn't check before i installed win7 ultimate x64 whether mobo was set to IDE or AHCI. found afterwards that there are 3 settings that are on IDE. these are:

PCH SATA Control Mode, GSATA3 Ctrl Mode and eSATA3 Ctrl Mode

to prevent reinstalling windows and programs, what i would like to know is,

can i change to AHCI in Bios after using the Reg Change above?

will i have to change all the 3 IDE settings used atm to AHCI, if not what one(s) do i change?

will i have to install the Intel AHCI drivers afterwards and perhaps other drivers as well? if so, which ones?

will it kick out my o/c?

anything else i need to know or will have to do?

hope someone can advise.

many TIA

Grand Master

TheLegendOfMart

Posted
Posted

1) Thats the only way to do it, you cant change to AHCI in the bios before you do the reg change or Windows will fail to boot

2) Yes change them all to AHCI

3) If you already have Intel drivers installed I think the drivers should already be cached so once it detects AHCI it should already have the drivers

4) No your o/c is fine

5) Nothing else to know

Apprentice

kevpc

Posted
Posted

many tnx for replies, guys. one more question, if you dont mind. forgot to ask this with other questions. if i change the registry as instructed but dont then change in the bios but leave it at IDE, will that have any adverse affects? did try to install the Intel AHCI, but was told 'this computer does not meet the minimum requirements for installing the software', so assume no AHCI drivers installed at all atm?

tnx again for help

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