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How to determine if system is in AHCI mode?

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How to determine if system is in AHCI mode?

  • Hi,

    I have an Inspiron 530 Desktop (2 HDDs, non-RAID) that came with Vista Home Premium preinstalled. It didn't take too long until I decided to downgrade to XP Pro SP2...

    Before installing XP I wanted to make sure that AHCI was enabled in the BIOS (mainboard features an ICH9R so I was confident the option would be there) but to my surprise I was only presented the two options IDE and RAID. Dell support told me that the IDE option would have the same effect as AHCI and that the drives (Samsung Spinpoint series) would operate in AHCI mode anyway - so I left it at that.

    I installed XP using an nLite'd installation disc containing the AHCI driver for my chipset. Installation went fine but I suspect that the system doesn't operate in AHCI mode since

    1) Intel Matrix Storage Manager for XP didn't install and
    2) the "IDE ATA/ATAPI controllers" section in the device manager doesn't show an "Intel(R) 82801IR/IO SATA AHCI Controller"

    Is there a reliable way to tell if the system is in AHCI mode? And if it is, why does the Matrix Storage Manager installation fail?

    Any help would be much appreciated.

  • My understanding is the opposite. ATA mode is a primitive (maybe lower performance) backward compatible mode and that RAID mode is AHCI.

    Note that the two modes require different drivers and so you can't just change from one mode to the other and expect Windows to boot (at least that is what I and others have found). You either need to reinstall Windows or install the drivers manually and change some registry values(Microsoft describes what to do ... it is very easy).

  • Quote from Intel*:

    "Serial ATA (SATA) modes

    The SATA controller has three modes of operation:

    * IDE mode - no AHCI, no RAID
    * SATA mode (sometimes called AHCI mode) - AHCI enabled, no RAID
    * RAID mode - AHCI enabled, RAID enabled

    NOTE: Your system may not have all three options, depending on the motherboard manufacturer and model."


    I'm not talking of (P)ATA (which is old) but SATA.

    Anyway, I figured out that choosing IDE really is just the IDE mode (without AHCI), which is contrary to what Dell support told me. I can tell because I managed to install XP again without any supplementary driver and it works just the same. Moreover the driver used for the controller is pciide.sys.

    So my next question would be: if we can't enable SATA mode (AHCI enabled, no RAID) in the BIOS, can we enable RAID mode (which implicitly enables AHCI) and then just choose not use the RAID feature but to have 2 independent disks operating in SATA mode?

    I'm asking because I want to be sure that I can enable the RAID option without messing up the data on my second hdd.
  • On my machines I have RAID on, but no RAID operating. That is SATA ACHI mode.

  • That sounds interesting.

    So you just set the "SATA Mode" option in the BIOS to "RAID", reinstall XP using SATA drivers and you're done?

    Does the switch from IDE to RAID affect the data on the 2nd HDD?

  • That will work, but you can get buy without reinstalling Windows (I don't have link, but Microsoft has complete instructions). A repair install should also do it.

    It will not affect the data on the HD.

  • Thanks, Peter. I finally tried it - works without problems! :)
  • haiduc, may I ask which drivers you ended up slipstreaming with nlite?


    Intel(R) ICH8R/ICH9R SATA RAID Controller


    Intel(R) ICH9 SATA AHCI Controller


    and via which inf... iaahci.inf or iastor.inf... it seems clicking on either in nlite bring up all possibilities anyway but I wonder if there's a difference is all.



    ~ Steph


    Message Edited by skoenig on 04-10-2008 05:32 AM