How To Enable AHCI/RAID In Windows 8 For Enhanced Performance

Currently, SATA (Serial ATA) hard drives are being used widely because of their enhanced performance, better throughput  and other features. Previously PATA (Parallel ATA) was being used which is being replaced by SATA technology.  The Advanced Host Controller Interface (AHCI) is a technical standard defined by Intel that specifies the operation of Serial ATA (SATA) host bus adapters in a non-implementation-specific manner. In simple words, AHCI technology is used with SATA ports in order to make use of SATA’s advanced capabilities. Currently AHCI v. 1.3 is being used widely.

AHCI enables advanced capabilities of SATA to be used like hot swapping and native command queuing. Hot swapping is a great feature usually present in RAID systems in which the hard drive can be plugged out or plugged in without turning off the system. If a SATA hard drive is plugged in with AHCI enabled, it will automatically be detected by the system without needing to restart.

Native command queuing is another great feature which lets the hard drives self optimize themselves resulting in better performance for workloads where multiple simultaneous read/write requests are outstanding. To understand this phenomenon, see the picture from Wikipedia given below:

Native command queuing

AHCI is supported in Windows Vista, Windows 7 and Windows 8.

Enable AHCI In Windows Vista/Windows 7

Enabling AHCI in Windows Vista and Windows 7 is quite simple. You will need to enable it through Windows registry.

  1. Open Registry Editor (Run –> regedit). Go to the following registry key:
    HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\services\\msahci
  2. In the right hand pane, make sure the value of “Start” key is set to 0.
    Enable AHCI in Windows 7
  3. Now restart the computer and enable AHCI mode from BIOS.

This was the method for enabling AHCI in Windows Vista and Windows 7. The registry key for enabling AHCI in Windows 8 is different. Follow the steps below in order to enable AHCI in Windows 8:

  1. Open Registry Editor (Run –> regedit). Go to the following key:
    HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Services\\storahci
  2. In the right hand pane, make sure the value of “Start” key is set to 0.
  3. Now restart the computer and enable AHCI mode from BIOS.

If you are not comfortable working with the Windows registry, you can download and open the following registry file. Just merge it and it’ll automatically do the hard work for you.

[download id=”43″]

Enable AHCI In Windows 8

  1. Before enabling AHCI mode in Windows 8, you should make sure that the AHCI driver for your chipset is already installed in Windows 8 otherwise you will still get INACCESSIBLE_BOOT_DEVICE error.
  2. Delete the entire StartOverride key in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\(DriverNameHere). You can also set its value to 0 which should also work.
  3. Restart the computer and enable AHCI mode from BIOS.

6 thoughts on “How To Enable AHCI/RAID In Windows 8 For Enhanced Performance

  1. What do you mean Delete the entire StartOverride key in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\(DriverNameHere). You can also set its value to 0 which should also work.

    Which driver do i delete as there are so many ? Do you want me to delete the “Start” in the storahci folder?

    Reply

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