ARTICLE: Enable AHCI Technology in Windows

At its onset, SATA technology promised a lot of improvements. It was considered the mainstream hard drive's best thing since sliced bread. Speed being one of its many promises along with hot swapping and native command queuing. And now, AHCI (short for Advanced Host Controller Interface) was brought to SATA. We know what SATA is, but what is AHCI?

According to Wikipedia:

The Advanced Host Controller Interface (AHCI) is a technical standard defined by the Intel Corporation that specifies the operation of Serial ATA (SATA) host bus adapters in a non-implementation-specific manner.
The specification describes a system memory structure for computer hardware vendors to exchange data between host system memory and attached storage devices. AHCI gives software developers and hardware designers a standard method for detecting, configuring, and programming SATA/AHCI adapters. AHCI is separate from the SATA 3Gb/s standard, although it exposes SATA's advanced capabilities (such as hot swapping and native command queuing) such that host systems can utilize them.

To complicate things even more, motherboard manufacturers have this BIOS setting to enable and disable AHCI. And worse, Windows has this technology disabled by default. If this technology promises performance improvements, then why not take advantage of the technology right? Afterall, you bought a system that has this technology and in essence, you paid for it! Might as well put it to good use.

Follow the procedure below:

[1] Assuming you already have a Windows 7 system, fire-up the registry. Start > Run > regedit.

[2] If the UAC window pops-up and nags if you want to proceed, just click "Yes".

[3] Open the branch: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\msahci

[4] Right-click on the "Start" key and select "Modify". Set the value to "0" (Automatic). The unmodified default should be "3" (disabled).

[5] Close the registry editor and reboot for the change to take effect.

The default setting of most motherboards for AHCI is disabled. After the computer has shutdown, it is recommended to enter the BIOS and enable AHCI first then allow it to reboot. If unsure how to get to the settings, consult your motherboard manual or the website of its manufacturer.

Your computer system may have this technology already. As mentioned, might as well make the most out of it.