BSOD during boot after disabling RAID in BIOS

The motherboard of my Acer M3920 has an on-board RAID controller which is part of the Intel Rapid Storage Technology. I added a 6TB WD Green drive, which was very easy using the easy-swap bay that the Acer M3920 has (see picture below). Unfortunately the RAID BIOS did not recognize the drive I inserted into the machine. The normal BIOS did recognize it, but in the RAID BIOS it was reported as a 1.4TB disk. Also Windows 7 Disk Management did not “see” the drive.


Normally I would have updated the BIOS (as this would have likely solved the problem), but I could not find a newer BIOS on the Acer support site. So I decided to turn the RAID support off in the BIOS (switch the SATA mode from “RAID” to “AHCI”), since I did not used the RAID capabilities. This caused Windows to give a BSOD during boot with message “STOP: 0x0000007B” (see picture below). This actually is a cryptic way of Windows telling you “INACCESSIBLE BOOT DEVICE”.


To avoid this error, the instructions in Microsoft KB article 922976  are not sufficient. They are sufficient when changing from AHCI to RAID, but not when changing from RAID to AHCI. Use the “regedit.exe” utility to change the “Start” key to value “0” for both of the following entries in your registry:

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\msahci (as mentioned in the KB)
  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\atapi (not mentioned in the KB)

If you have this BSOD, reboot and set the SATA mode (in the BIOS) back to RAID. Then reboot and change the above registry settings. Finally change the SATA mode to “AHCI” and boot without BSOD and full access to your 6TB drive.

Special thanks go to M



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