Windows 8 and AHCI

Discussion in 'Windows 8' started by nivong, May 2, 2012.

  1. nivong

    nivong MDL Novice

    Feb 6, 2012
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    #1 nivong, May 2, 2012
    Last edited by a moderator: Apr 20, 2017
    So I had a problem with windows 8 and AHCI and there isn't much information about windows 8 and AHCI...

    My problem:
    I installed windows 8 using AHCI mode and all went well. windows 8 was running good with AHCI and no other OS installed.

    So I wanted to check if there was a big speed difference in windows 8 with AHCI turned on, so I decided to turn it off.
    Regedit:
    Code:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\storahci
    and In the Value data box of the Value "Start", type 0, and then click OK.
    so I restarted, enterd BIOS and disabled it.
    After restarting windows 8 started succesfully and I noticed some speed difference, so I wanted to go back to AHCI. BUT NO! windows 8 failed, blue screen after blue screen.... Inaccasible_boot_device.....

    After many fail and errors I found out that if you change
    Code:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\storahci
    back to 3 (to enable it) you also need to edit the following:
    Code:
    HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\CriticalDeviceDatabase\pci#ven_8086&dev_2922&cc_0106
    note: this can be different:"ven_8086&dev_2922&cc_0106"
    Now you will also need to change the Service back again to storahci to get it back again! to do that set the following:
    Code:
    "Service"="iaStor"
    Now you can use windows 8 with AHCI again.

    I hope I helped some of you guys that also had the same problem :)
     
  2. nivong

    nivong MDL Novice

    Feb 6, 2012
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    #2 nivong, May 3, 2012
    Last edited by a moderator: Apr 20, 2017
    (OP)
    Supports NCQ (Native Command Queuing) allowing SATA drives to accept more than one command at a time and dynamically reorder the commands for maximum efficiency.

    More information about this tech:
    Code:
    en.wikipedia.org/wiki/Native_Command_Queuing
    And I noticed some startup improvements but
     
  3. denisw705

    denisw705 MDL Junior Member

    Dec 10, 2010
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    this build not support the SATA - AHCI !!!!
     
  4. nivong

    nivong MDL Novice

    Feb 6, 2012
    33
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    #4 nivong, May 10, 2012
    Last edited: May 13, 2012
    (OP)
    and how do you know that? As far for me it's working great. I can hot swap my hard disks without any problem and boot is a full second faster (woooohooo)

    have you did any research? I don't think so....
     
  5. ashmicro

    ashmicro MDL Junior Member

    Mar 2, 2012
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    SATA/AHCI working fine here.
     
  6. marcelcraig

    marcelcraig MDL Novice

    Dec 30, 2012
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    simpler solution

    This thread got me close to the solution but not all the way so I wanted to post to help others. The registry edit solution doesn't always work because the ahci driver can go by many different names and you may have duplicates in your registry if you've for example installed updated ahci drivers that enter into the registry under a slightly different name. There is a much easier way than editing the registry, it's quite silly actually, all you need to do is set your Win8 to temporarily boot in safe mode on next boot, then restart and edit your bios to turn on ahci mode before booting into windows safe mode. Then Windows will boot into safe mode and automagically adapt to the ahci mode. Then set windows to boot normally next time, restart, and viola! Full instructions on MS tech note kb2751461
     
  7. pisthai

    pisthai Imperfect Human

    Jul 29, 2009
    6,642
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    IDE - AHCI isn't supported, SATA - AHCI is, at least in those MB's which has an BIOS which supports RAID. After AHCI is enabled and windows gets installed after that, AHCI is automatically installed and enabled and if you use some IDE HDD's in Removable Cases, it also work for IDE but slow for startup those IDE HDD's.
     
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