Advanced Host Controller Interface (AHCI)

Many SATA controllers can include the simple AHCI mode or with support of RAID. Intel recommends to select on the motherboards the mode with support of RAID (at the included AHCI) for bigger flexibility.

The built-in support of AHCI is included in Mac OS X (since Mac OS X 10.4.4 for Intel), Microsoft Windows (since Vista), Linux (since a core 2.6.19[2]), NetBSD, OpenBSD (starting with version 4.1), FreeBSD, Solaris 10 (since release 8/07). Older operating systems require the driver of the producer.

Support of AHCI exists not in all chips of south bridges, but even at its implementation in the chip the producer of the motherboard can not implement it in BIOS, and it will be unavailable. Sometimes the problem is solved pereshivaniy BIOS, there are unofficial pravleny firmwares for many motherboards.

In certain cases (Asus P5KC) support of AHCI cannot be included on the south bridge, but it is possible to include on the separate chip working at outdated Parallel ATA the connector in the body or through external eSATA the connector. It turns out that internal hard drives cannot use AHCI, and the external body connected on eSATA with a disk - can. Switching of the south bridge from normal PC/AT on AHCI means involvement in it absolutely of other, incompatible logic of the ATA controller. In terms of OS it is equivalent to installation of a payment of the proprietary ATA controller in the slot and physical switching of a boot drive to this payment, or transfer of a disk from the installed OS in other body with other proprietary ATA controller.

In this case Windows will not find an own boot drive and will under abnormal condition stop on INACCESSIBLE_BOOT_DEVICE when loading. For solution it is necessary to set one way or another the AHCI driver (or the driver of the proprietary controller) in Windows even before physical switching that can be difficult because at this moment there is no device serviced by the driver. Nevertheless the problem is solved by changes of the register, connection of the second hard drive, etc.