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Windows 7: AHCI : Enable in Windows 7 / Vista

21 Aug 2015   #590

Windows Vista Ultimate 32bit

I did follow the correct registry edit and BIOS sequence, except for the problem with AHCI not being an available option in the BIOS. When the eSATA drive (port) is displayed in the BIOS, it says that in order for eSATA to work, the BIOS must be set to AHCI or RAID (even though AHCI is not available).

Here's the latest:
Instead of resetting the CMOS, I tried changing the BIOS to RAID (again). The eSATA drive was on before starting Windows, and Windows detected it (appears in Computer...). Next I tried hot swap (this is actually hot turn on, I haven't yet tried turning it off while Windows is running, sounds risky since I see no way to tell Windows to "remove" it as can be done with USB): turn off the PC, turn off the eSATA drive, start the PC, Windows starts ok, then turn on the eSATA drive. This time the eSATA drive is detected - shows up in Computer, but within 3 sec it disappears . Using device manager to scan for new h/w, the eSATA drive becomes available again and stays available. This scenario was repeated twice, with the same results. On the next try, hot swap worked as it should - after turning on the eSATA drive it became available and stayed that way, no need to scan for new h/w. Thought I was home free.

The next day I tried hot swap and immediately got BSOD. Right after that I tried hot swap again, and this time it worked as desired. I hope the system will settle down and continue to work properly. If problems continue I'll just avoid hot swapping, or if time permits I may eventually try reset of CMOS.

Thanks again for your feedback and tips.

My System SpecsSystem Spec
21 Aug 2015   #591

Windows 7 Pro 64-bit

At this point, I can't offer any more help based on actual 1st-hand knowledge, other that that I suspect a possible cable problem or a bad controller either on the mobo or inside the drive. Suggestions:
  • try a different cable
  • try another eSATA port
  • try a different drive
Best of luck. Please post any good or bad results.
My System SpecsSystem Spec
27 Sep 2015   #592


I wanted to do the same on my win 8.1 installed. I set AHCI mode in BIOS before install, but windows says it is still IDE (samsung 850 evo SSD), I looked in the registry and I do not have "msahci" there.

I looked at iaStorV, but the start value is 0, then I looked in StartOverride and REG_DWORD is 3, do I change it too 0 to get AHCI mode?

EDIT: I just found an old post from Brink in 2013 that told me to use iaStorv.

EDIT 2: Did the change from 3 to 0, but Samsung Magician still says IDE mode, even though BIOS says AHCI mode.

Attached Thumbnails
AHCI : Enable in Windows 7 / Vista-clipboard01.jpg  
My System SpecsSystem Spec
29 Oct 2015   #593

Windows 7 Ultimate 64

I have a variation on a theme, I have an installed Win 7 Ultimate running in IDE with a Samsung 500gb EVO and found the tutorial to be helpful. I thought I would try finding the setting in BIOS before updating the registry but found that it is near impossible to get into the bios as the computer boots too fast. I am wondering if I apply the changes to the registry as per the tutorial and then use Gigabyte TouchBios to change the SATA mode to AHCI and then reboot if that will work? Any advice appreciated.
My System SpecsSystem Spec

29 Oct 2015   #594

64-bit Windows 10 Pro

Hello Andy, and welcome to Seven Forums. :)

As long as both get changed, it should be fine.
My System SpecsSystem Spec
29 Oct 2015   #595

Windows 7 Ultimate 64

Thanks Brink. Will give it a shot.
My System SpecsSystem Spec
30 Oct 2015   #596

Windows 7 Pro 64-bit

Just be sure you maintain the sequence of changes.
My System SpecsSystem Spec
31 Dec 2015   #597

Windows 7 64bit
I've tried all these fixes but it still fails

I've tried these fixes but when I change my bios from raid to ahci I get a flash of the deadly blue screen and then directed to Windows repair. I have an Alienware m17xr4 with an Intel core i7 3630qm board, Windows 7 runs well, but after migrating my os to a Samsung 850 Pro I wanted the speed promised with ahci. I've tried using my restore point in Windows recovery on startup but no good, do I really need to reinstall Windows and all the Alienware drivers then all my programs to get it to accept the change to ahci
My System SpecsSystem Spec
02 Jan 2016   #598

Windows 7 64bit
Switched from RAID to AHCI no joy Windows 7

I've updated my board driver Intel core i7 3630QM which installed correctly, I've used the fixes described in threads here, but after changing bios to AHCI, the dreaded blue screen then a reboot to Repair startup, Alienware M17 XR4, no joy, now back to RAID with a slight diversion to startup repair.

I've even completed a clean install on my Samsung Pro 850 SSD using Windows 7 disk, still refuses to start.

What am I doing wrong
My System SpecsSystem Spec
31 Jan 2016   #599

Win 7 Ult SP1/Win 10 Pro (all x64)

Can this process be reversed safely (if no restore point available) ?

I ask because now Diskeeper can't read the SMART status of my external drive, before it could + quite hoebstly I see no improvement in performance.

Answered my own question, yes it ignore this post.
My System SpecsSystem Spec

 AHCI : Enable in Windows 7 / Vista

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