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IDE or AHCI

    Question

  • Just out of curiosity is there any big difference or pors/cons between using IDE or AHCI mode in Win7? I notice I can supposedly switch to AHCI mode by changing a registry key rebooting changing a setting in the Bios and then re-entering Win7 where it will then install a driver that will enable AHCI mode but am curious if its worth the change. Currently my SATA drives are running in IDE mode and I know if I switch to AHCCI then NCQ would be enabled on the 1T drives I have.
    Wednesday, June 03, 2009 10:20 PM

Answers

  • I go back and forth on this.  I don't see (or feel) much difference on Windows of any flavor, including both 32-bit and 64-bit versions of XP and Vista and the 64-bit version of the Windows 7 release candidate. 

    It makes a bigger difference on my Linux machine, but that's mostly because development of the straight PATA driver mostly stopped a long time ago and the S-ATA disk driver in the kernel performs better and is more stable.

    I have experienced a couple of older S-ATA optical drives (Plextor PW-16SA) that did not work very well when the S-ATA controller was set to SATA as AHCI mode in BIOS and the AHCI driver loaded into windows XP.  My work-around was to connect them to the motherboard's secondary S-ATA/RAID controller and leave that set to IDE mode in BIOS.  The hard drives are connected to the Intel ICH controller and that runs SATA as AHCI mode.  I have not had to do that with newer optical drives...they seem to work fine in the SATA and AHCI mode.

    • Marked as answer by axfelix Thursday, June 04, 2009 1:09 AM
    Wednesday, June 03, 2009 11:14 PM

All replies

  • I go back and forth on this.  I don't see (or feel) much difference on Windows of any flavor, including both 32-bit and 64-bit versions of XP and Vista and the 64-bit version of the Windows 7 release candidate. 

    It makes a bigger difference on my Linux machine, but that's mostly because development of the straight PATA driver mostly stopped a long time ago and the S-ATA disk driver in the kernel performs better and is more stable.

    I have experienced a couple of older S-ATA optical drives (Plextor PW-16SA) that did not work very well when the S-ATA controller was set to SATA as AHCI mode in BIOS and the AHCI driver loaded into windows XP.  My work-around was to connect them to the motherboard's secondary S-ATA/RAID controller and leave that set to IDE mode in BIOS.  The hard drives are connected to the Intel ICH controller and that runs SATA as AHCI mode.  I have not had to do that with newer optical drives...they seem to work fine in the SATA and AHCI mode.

    • Marked as answer by axfelix Thursday, June 04, 2009 1:09 AM
    Wednesday, June 03, 2009 11:14 PM
  • Worth reading:
    Advanced Host Controller Interface
    http://en.wikipedia.org/wiki/Advanced_Host_Controller_Interface

    Also read the "Common Problems" section.
    JS
    Thursday, June 04, 2009 1:13 AM
  • Well I followed the MS KB article about how to change to AHCI and everything seemed to go well. Is there a way to confirm that the system is now running in AHCI mode?
    Wednesday, June 10, 2009 8:10 PM
  • Other than the BIOS configuration none that I'm specifically aware of.

    There is a utility named HD Tune (Free version) to test drive performance:
    http://www.hdtune.com/

    Some HD Tune test results:
    http://forum.notebookreview.com/showthread.php?t=259331
    JS
    Wednesday, June 10, 2009 8:31 PM
  • You should see something like "Intel(R) ICH9 SATA AHCI Controller" under IDE ATA/ATAPI controllers in the Device Manager.

    EDIT: Also, I believe the IaStor service runs only when AHCI/RAID is enabled. I switched back to IDE because of driver/corruption/dead hard drive issues so I don't remember and it's currently not there.
    • Edited by Ryan Capp Thursday, June 11, 2009 7:35 AM
    Thursday, June 11, 2009 7:31 AM
  • Well I don't see any iastor service running. When I did the "switch" following the MS kb guide I first went and changed the reg key from 3 to 0 and rebooted and went into the bios. Then from there I changed that to AHCI, saved and rebooted. Win7 booted up and I got a window saying installing drivers etc which is what I had read in the kb was the expected outcome.

    I went into Device manager and looked and I have listed:
    • IDE ATA/ATAPI controllers
    -ATA Channel 0
    thru
    -ATA Channel 5
    -Standard AHCI 1.0 Serial ATA Controller

    Then I decided to check devices by connection and if I go to the PCI bus section and then click
    -Standard AHCI 1.0 Serial ATA Controller
    It list ATA Channels 0-5 and under the different channels each one lists one of my drives thats connected so I guess its working.

    Wonder why I don't see an iastor service running tho, unless it has to do with me using the MS driver vs the Intel version.
    Thursday, June 11, 2009 12:05 PM