AHCI and IDE are two modes in which a hard drive communicates with the rest of the computer system using a SATA storage controller. SATA hard drives can operate in a backward-compatible PATA/IDE mode, a standard AHCI mode or vendor-specific RAID. AHCI stands for Advanced Host Controller Interface and is a faster mode of operation compared to IDE. RAID mode also enables and makes use of AHCI.
AHCI provides a standard system that designers and developers can use to configure, detect, or program SATA/AHCI adapters. Note that even though AHCI taps into the more advanced features of SATA (e.g., hot swapping) for host systems, it is a separate standard from those set for SATA.
|Stands for / AKA||Advanced Host Controller Interface||IDE: Integrated Drive Electronics / PATA: Parallel Advanced Technology Attachment|
|Advantages||Supports new technologies such as native command queuing||Maximum compatibility|
|Hot plugging (add/remove component while the computer is running)||Supported||IDE interface does not support hot plugging|
|Disadvantages||Not always compatible||Lacks support for new technology such as native command queuing and hot-plugging hard drives|
|Defined by||Intel||Western Digital|
|Involves||Operation of Serial ATA (SATA) host bus adaptors||Operation of a parallel ATA drive|
|Operating modes||Legacy Parallel ATA emulation, standard AHCI or vendor specific RAID||IDE|
|Operating system support||Windows Vista, 7, and 8; Linux, OpenBSD, NetBSD, FreeBSD, OS Z, eComStation and Solaris 10||All|
edit Operating Modes
IDE only has one operating mode. But AHCI is a newer standard that was designed to be backward-compatible with legacy systems that could only "speak IDE". So AHCI offers several modes of operation: legacy Parallel ATA (Parallel ATA, PATA and IDE are the same thing) emulation mode, standard AHCI mode or vendor-specific RAID. Intel recommends the use of RAID mode on their motherboard, as it is more flexible.
edit Advantages of AHCI over IDE
IDE is considered adequate for the average computer user, and is the most compatible with other technology, particularly older devices. However, it lacks support for new technologies.
AHCI supports some important new features that IDE does not, such as native command queuing and hot-plugging hard drives. It also offers an improvement performance (speed) over IDE.
edit How to Enable AHCI Mode to Boost Performance
The video below shows how to enable AHCI mode in SSD (solid state drive):
AHCI is supported by all versions of Windows Vista and newer, Linux and Mac OS. However, Windows does not configure itself to load the AHCI driver upon boot if the SATA-drive controller was not in AHCI mode at the time of installation. So the PC will not boot up if the SATA controller is later switched to AHCI mode. The drive controller should be changed to AHCI or RAID before installing the operating system.
edit Operating System support
IDE is supported by all operating systems.