How do I change from IDE to ACHI?

You can only the setting in your BIOS if you have a SATA drive and a motherboard that has a SATA controller. You also can only use AHCI if your OS has the drivers installed. Windows XP does not have native SATA drivers, they can be can be intalled after the installation of the OS, but must be installed before the BIOS change. Windows Vista and Windows 7 have native SATA drivers, but again they have to be installed before the BIOS change. The following link describes haow to install the SATA drivers for Windows XP on a motherboard with a Intel chipset: http://saysprasad.wordpress.com/2009/02/01/installing-s...

1. Startup "Regedit
2. Open HKEY_LOCAL_MACHINE / SYSTEM / CurrentControlset / Services
3. Open msahci
4. In the right field left click on "start" and go to Modify
5. In the value Data field enter "0" and click "ok"
6. exit "Regedit"
7. Reboot Rig and enter BIOS (hold "Delete" key while Booting

In your BIOS select "Integrated Peripherals" and OnChip PATA/SATA Devices. Now change SATA Mode to AHCI from IDE.

You now boot into windows 7, the OS will recognize AHCI and install the devices. Now the system needs one more reboot and voilla .. enjoy the improved SSD performance.

I cheated, Quote from: http://forums.guru3d.com/showthread.php?t=313676

I knew that sounded familiar.