TweakTown's Ultimate Windows SSD Performance Installation Guide (Page 10)

| Nov 5, 2014 at 5:05 pm CST

AHCI to RAID or RAID to AHCI

So, you've decided that you want to change storage modes for one reason or another. You go into your BIOS, and change your storage mode from AHCI to RAID, or RAID to AHCI, and reboot only to be greeted with a BSOD. Looks like you will have to reinstall Windows, which sucks because you have a million programs installed and running just right.

Well, there is an easy way. A quick couple of registry changes, and you will be able to boot into Windows in the storage mode of your choice. Make these registry changes, and Windows will boot up with the appropriate driver for the storage mode you want to change, without having to reinstall Windows and all that software.

Typically, users want to change from AHCI mode to RAID mode after learning how much better storage performance and flexibility RAID has to offer. Let's cover that scenario first. The first step is to open Windows registry editor. In your search bar, type "regedit,"then right click on the icon that pops up, and select "run as administrator."

Windows 8 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services storahci.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the zero to a three. Entering a three disables the startup of a driver, and we want to disable the startup of the AHCI driver, and load the RAID driver instead.

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Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services msahci.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the zero to a three.

Next, we need to enable the RAID driver to start up at boot.

Windows 8 users, navigate to: HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorV StartOverride.

Right click on "REG_DWORD," and change the value data from three to zero.

TweakTown's Ultimate Windows SSD Performance Installation Guide 124 | TweakTown.com

Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorV.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the three to a zero. Hit "OK," and exit the Registry Editor.

Now, reboot, enter your motherboards BIOS, and change SATA Mode from AHCI to RAID. Reboot again, and Windows will load with the built-in Windows RAID driver.

At this point, if you were running an IRST storage driver, you will need to uninstall it, and then re-install it for functionality.

If you want to be able to switch from AHCI to RAID, and back again, then you can just leave both registry entries set at zero. If you are running an IRST driver, and want to have the capability to switch modes at will, then you need to change one more registry entry from three to zero.

Windows 8 users, navigate to: HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorAV StartOverride.

Right click on "REG_DWORD," and change the value data from three to zero.

TweakTown's Ultimate Windows SSD Performance Installation Guide 125 | TweakTown.com

Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorAV.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the three to a zero. Hit "OK," and exit the Registry Editor.

Now you can change from RAID to AHCI. There is really no reason I can think of to do this maneuver, unless you want to run a single drive and enable caching software that only functions in AHCI mode. To go backward, as it were, just do the exact opposite:

Windows 8 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services storahci.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the three to a zero.

Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services msahci.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the three to a zero.

Next, disable RAID driver.

Windows 8 users, navigate to: HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorV StartOverride.

Right click on "REG_DWORD," and change the value data from zero to three.

TweakTown's Ultimate Windows SSD Performance Installation Guide 126 | TweakTown.com

Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorV.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the zero to a three.

You may want to disable the IRST RAID driver as well.

Windows 8 users, navigate to: HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorAV StartOverride.

Right click on "REG_DWORD," and change the value data from zero to three.

Windows 7 users, navigate to:

HKEY_LOCAL_MACHINE System CurrentControlSet Services iaStorAV.

Right click on the "Start" parameter, hit "modify," and edit the value data, changing the zero to a three. Hit "OK," and exit the Registry Editor.

Now, reboot, enter your motherboards BIOS, and change SATA Mode from RAID to AHCI. Reboot again, and now Windows will load with the built-in Windows AHCI driver.

At this point, if you were running an IRST storage driver, then you will need to uninstall it, and then re-install it for functionality.

Last updated: Apr 7, 2020 at 12:33 pm CDT

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ABOUT THE AUTHOR -

Jon became a computer enthusiast when Windows XP launched. He was into water cooling and benching ATI video cards with modded drivers. Jon has been building computers for others for more than 10 years. Jon became a storage enthusiast the day he first booted an Intel X25-M G1 80GB SSD. Look for Jon to bring consumer SSD reviews into the spotlight.

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