AHCI Problem

Bemused One

Distinguished Member
I sure hope someone can help me out with this because it's starting to drive me nuts! :mad:

Whenever I change the SATA AHCI Mode from IDE to AHCI in the BIOS of my new build, then reboot, when I return to the BIOS my HD (a Sammy F3 no less) has disappeared! For some reason the BIOS no longer recognises it. Stranger still, even though it no longer appears under standard CMOS features, it does appear when I check the hard disk boot priority, under advanced BIOS features. What is going on at all?

Has anyone else ever experienced the above and is there a solution to it? Any help, suggestions, advice would be greatly appreciated. I'm bursting to get this sorted out because it's delaying the installation of my new OS. Please help me someone! :lease:

Bemused One

Distinguished Member
Okay, let me ask these things then.

To all of you folks who have AHCI enabled and working properly, do the drive or drives running in AHCI mode disappear from your BIOS, or are they still visible? Also, do the drive or drives appear in your OS's device manager?


Standard Member
Hope you don't take this wrong but have you done a search of this forum?
I went looking for information about AHCI for my new build and found a lot of threads on the subject. One that may help you is:-

If you have Windows 7 already installed and you did not enabled AHCI before installation, you won't be able to enable it now (it won't work), becuase when you install Win 7 without AHCI enabled it thinks that AHCI is unavailable for you and the Windows AHCI drivers won't be installed.

From what I understand, there are 2 ways to cure it if you want to use AHCI.

1. is to reinstall Windows
2. is to edit registry and change one value.

all of that has to be done before enabling AHCI in BIOS (it won't detect any drives).

If you want to registry edit give a go, here is what you need to change:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\Msahci
change the 'start' entry to have a value of 0

Bemused One

Distinguished Member
Thanks to you both for the information.

@ Oarsman - Yes I did a search of this forum to find out what information I could about AHCI.

My original post was before I installed my OS. All I had done at that stage was change the BIOS setting from IDE to AHCI. Rather than rebooting and let Win 7 install, I returned instead to the BIOS and was puzzled as to why my HDD had disappeared. I didn't think this was normal, in fact I still don't, hence my post for help.

Since my original post I've installed Win 7, making sure the AHCI value was selected in the BIOS beforehand. Everything installed without any problems, however my SATA HDD still doesn't appear in the BIOS and it's not visible in the device manager of my OS either. What I want to know is, is this normal? Is this right? Or do I have a problem?

So let me ask you, and indeed anyone who has AHCI working properly, are your SATA HDD's visible in both your BIOS and device manager with AHCI enabled?
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Established Member
If you use the Intel ICHx(R) controller, when you select AHCI (in the BIOS), the HDDs will disappear from the main BIOS page (which show the HDDs when in IDE mode), but they will be available on the Boot (Priority) page and will be visible on the AHCI screen when the comp. begins to boot into Windows...this is the normal behaviour.

Bemused One

Distinguished Member
Thank you so much for your reply, jbloggs, it's made me feel a lot better. :)

I can confirm my SATA HDD is visible in the boot priority section of the BIOS, but it's been difficult for me to catch the AHCI screen at computer boot up because it just flies by so fast. Is there any way to slow it down somehow so I can see what it says?

Can I just ask, when in AHCI mode, what should the IDE ATA/ATAPI controller section of the device manager look like in Win 7?


Established Member
Mine (Gigabyte GA P55 UD5) looks like this:


Is there any way to slow it down somehow so I can see what it says?

Just after you power on and the BIOS screen appears, just as it is about to disappear, hit the "Pause Break" key on your keyboard and this will stop the boot process, by which time the the AHCI screen will have appeared and stopped, when you finish looking at the AHCI page, hit the "down arrow" to continue boot process...

Bemused One

Distinguished Member
Thank you once again for such a helpful reply, jbloggs, I really appreciate it. :)

My device manager has the same entry as the one in your screen shot, as well as three additional entries - ATA Channel 0, ATA Channel 1 and Standard Dual Channel PCI IDE controller. Are those both of my hard drives and my PATA DVD drive then? If so, then I'm a bit confused by the ordering because I don't have my first HDD connected to SATA 0 on my motherboard. I've got one HDD on SATA 1 and the other on SATA 2. Does the OS just order things a little differently or something?

The pause break button worked a treat and the AHCI BIOS is looking good. Both my hard drives are identified in it, so I'm pleased with that. :)


Established Member
ATA Channel 0, ATA Channel 1 and Standard Dual Channel PCI IDE controller

This entry will be for your IDE Channel, ie. for your PATA devices (DVD rewriter perhaps), I have mine disabled in the BIOS as I use a SATA DVD rewriter, hence why you don't see it in the screenshot.

In Device Manager, you will find your HDDs listed under "Disk Drives," I wouldn't worry about how they are listed...just as long as they are listed...

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