Switching to AHCI in BIOS

Common problems switching to AHCI under Windows

• Enabling AHCI in a system's BIOS will cause a 0x0000007B Blue Screen of Death STOP error (INACCESSIBLE_BOOT_DEVICE) on installations of Windows XP, Windows Vista or Windows 7 where AHCI/RAID drivers for that system's chipset are not installed; i.e., boot failure.^[5]
  Switching the chipset to AHCI mode involves changing the BIOS settings and will not work. Usually, manual installation of new drivers is required before enabling AHCI in BIOS.^[6][7] Alternatively, a "Repair" installation with the appropriate driver loaded during the setup process usually corrects the problem. For motherboards with more than one SATA controller (for example, most new Intel controllers don't have IDE controllers and manufacturers add an additional controller with both IDE and SATA support) another alternative is possible. The sata cable for the boot drive can be inserted into a port on one controller (which can be configured in IDE mode), allowing the machine to boot successfully with the other controller configured for AHCI mode. The AHCI drivers can then be installed in Windows without difficulty before swapping the cable back.
• For Intel chipsets (for example, Intel ICH9) drivers are available from either an OEM motherboard or computer manufacturer. For the Intel versions, the driver must be loaded before loading the OS (by pressing F6 as setup starts, then using the floppy disk when prompted). The Intel drivers will work for both XP and Vista. Also, in the case of ICH9, an unsupported method to enable AHCI on ICH9
  is available.
• When attempting to install Windows XP or a previous version on an AHCI-enabled system, setup will fail with the error message "setup could not detect hard disk drive..." since no drivers will be found for accessing the SATA controller/s.
  This problem can be corrected by either using a floppy disk or by slipstreaming the appropriate drivers into the Windows XP installation CD, or by turning on IDE emulation in the BIOS settings if it's available (usually labeled IDE mode, ATA mode, or COMPATIBILITY mode [versus AHCI mode and RAID mode]).
• Enabling AHCI in a system with Windows Vista already installed will result in a BSoD if SATA was configured in IDE mode during Vista's installation. Before enabling AHCI in the BIOS, users must first follow the instructions found at Microsoft Knowledge Base article 922976
  . This fix also works with the Windows 7 Beta.
• Enabling AHCI in a system BIOS on installations of Windows XP or Windows Vista will cause SATA Optical drives to disappear. A Hotfix for Windows Vista is available under the title: "SATA optical drives are not available after you start a Windows Vista-based computer."^[8] This problem was fixed in Vista SP1.
• Windows Vista installation process may take several hours on a system that uses an AMD/ATI SB600 Series chipset operating in AHCI mode.^[9]

Common problems switching to AHCI under Linux

• The AHCI controller does not work on AMD/ATI RS400-200, and RS480 HBA; and Nvidia nForce 560 chipset when MSI is enabled due to a hardware error. For AHCI to work, users must provide the "pci=nomsi" kernel boot parameter. With MSI disabled in this way, the PCIe bus can only act as a faster PCI bus with hotplug capabilities.
• The VIA VT8251 South bridge suffers the same fate but it can be circumvented with the "pci=nomsi" option to force detection of the chip. This has been tested to work on 2.6.26, 2.6.24 and 2.6.20 kernels.
• Under RHEL, CentOS and similar, if you change your BIOS to AHCI mode and do not have the AHCI drivers in your initrd then you will not be able to boot.