AHCI (Advanced Host Controller Interface) enables native command queuing and hot-plugging through SATA host controllers (Serial-ATA) for your hard drives. In many scenarios, it enables more efficient multi-tasking. Vista was the first Windows OS to support AHCI out of the box, whereas Windows 7 does the same. But an issue with AHCI is that if you install the OS without enabling AHCI in the BIOS, enabling it after installation will render your OS unusable. This is because Windows disable the AHCI driver since it is not needed during the installation.
There is one way to fix this, although you need to have knowledge of registry editing. The detailed steps from Microsoft are as follows:
To resolve this issue, enable the AHCI driver in the registry before you change the SATA mode of the boot drive. To do this, follow these steps:
- Exit all Windows-based programs.
- Click Start, type Regedit in the Start Search box, and then press ENTER.
- If you receive the User Account Control dialog box, click Continue.
- Locate and then click the following registry subkey:HKEY_LOCAL_MACHINESystemCurrentControlSetServicesMsahci
- In the right pane, right-click Start in the Name column, and then click Modify.
- In the Value data box, type 0, and then click OK.
- On the File menu, click Exit to close Registry Editor.
After this you’ll have to restart your computer, go to BIOS and enable AHCI. When you log in to Windows again, you’ll notice the installation of drivers for AHCI. Another restart will be required to finish the driver installation.
I’ve simplified the steps by Microsoft by exporting the registry key. Just download the following file and run it. You’ll still need to go through the steps of restarting your computer and enabling AHCI in the BIOS.
Hopefully, you’ll find a somewhat noticeable improvement in multitasking, especially if you’re a notebook user. Of course with the variety of PC hardware, experience many vary.
Disclaimer:
thanks worked for my evga x58 system
You're right – Windows keeps a few backups of the CurrentControlSet registry key (that is the CurrentControlSet001, etc, that you see) – used for recovery if something goes wrong. When running, the *currently used version* of the key is made available (mapped) as 'CurrentControlSet'.
Thank you, thank you, thank you!
Thank you so much, it worked fine for Win7 final and gigabyte ep45-ds3r
You're welcome :)
it just worked with windows 7 built 7600, GREAT :)
it just worked with windows 7 built 7600, GREAT :)
Great Guide!! method works flawlessly..
However can somebody help me to enable IDE after installing Win7 in AHCI mode??.. I get the BSOD after switching from AHCI to IDE in bios…
Works!! You’ve saved me from hours of frustration. I’ve got an ASUS P5B and Win7 x64. I bought an external eSATA drive and used your trick to enable it. Thank you!
does it works on AMD proc ? i use acer aspire 4540
Didn’t work for me :(. I have a Dell mobo with ICH9R. Dual boot Windows XP (32) and 7 Pro (64). Bios only has setting of IDE/RAID, but it looks like RAID encompasses ACHI. Was able to change XP from IDE to RAID buy following one of the guides online – big reg entry to id the hardware, copy intel driver file, set bios and reboot. I thought 7 would be much easier – not! I made the suggested reg entry enabling msahci, but still BSOD on boot when setting the bios to RAID. When back to IDE 7 is ok. I have triple verified the reg entry. Any suggestions?
Thanks!
thanks a lot. it works like a champ. but ide x ahci performance looks the same. thanks anyway.
Worked as advertised. The only new thing I noticed was that now the SATA drives, including the boot drive c: are included in the “safely remove hardware and eject media” icon. Of course, it won’t allow you to eject your boot drive:-)
Thanks for the info!
It worked perfectly for my P7P55D motherboard with Intel Core i5 750 / windows 7 bits, while the ASUS AHCI had refused to install, saying the OS was not compatible. Thanks a lot ! The result is brilliant, windows open much faster, although Windows Performance Index for my WD velociraptor stayed the same at 5,9.
Pascal – France
Thanks! I was just searching for that :)
Perfect !!
it´s for you Windows User.Not a Bug.It´s a feature….
It worked for my Dell Studio 14Z.
This was a problem for me – since I have a windows 7 UE that is “upgrade only” DVD (purchased from Academic Institution) – I have to install windows XP first, then install Windows 7. Problem is, windows XP would not install unless I change the HDD controller to ATA from the bios. Then after windows 7 installation is done, I had no way of going back to AHCI mode…
Thanks for the tip. MUCH Appreciated.