Choose (or not) AHCI over IDE in the PC’s BIOS settings

ahcibioshard drivepata

I've noticed in the BIOS settings of the newer PCs I own that I can configure the drive controller work either in AHCI (Advanced Host Controller Interface) mode, or else in IDE mode.

I'm suspecting that AHCI "performs" better, but I really don't know much about that from a practical standpoint. However, I've also noticed that certain programs (e.g. Ghost 2003) simply don't detect my hard drives if I choose AHCI mode. (AHCI = A Heck of Compatibility Issues?)

So … why does AHCI exist, why should I care and want to use it, and why/when should I not want to use it? Are there features of newer hard drives that require AHCI, and do they otherwise dumb themselves down when running in IDE mode?

Best Answer

You can see AHCI as the language which the controller uses to speak with the system. The disk can't see if AHCI is being used or IDE emulation. If you use AHCI, all Serial ATA features are available, while you don't need any drivers specific to your controller.

To actually use AHCI, the OS (whether that's Windows, Linux or even Ghost) has to have an AHCI driver. Windows Vista and 7 include the driver, but don't install it if the boot drive's controller doesn't have AHCI enabled. Similarly, the IDE driver doesn't get installed if the IDE controller is disabled. That's why you can't just toggle the setting in the BIOS on an already installed Windows system.

Ghost 2003 was released in 2002, a few years before the AHCI specification was completed. It's hardly surprising that Ghost 2003 doesn't support AHCI. Apparently the latest enterprise version of Ghost can run in a boot environment based on either Windows or Linux, so it's likely that version does support AHCI.