Fix Window 7 From IDE to AHCI

Sometimes the bios setting for SATA drive is IDE mode by default and we installed windows XP or windows 7 with this setting. Later on, we want to change the bios setting to AHCI to install Mac OS X, we need to re-install windows or fix the registry to run with AHCI mode. We have to do this in windows before the bios is set or we will crash the windows os. Windows 7 or windows XP should have the same registry for msahci. The pictures of the bios here are award bios Gigabyte P55A-UD3 F11. Most of the newer motherboards or computer should have the SATA options AHCI except some old ones don’t have the option. Make sure the AHCI option exists in the bios before changing the registry because if we change the windows registry and the bios doesn’t support AHCI then we will be in trouble.

Click Start-regedit

type regedit and hit enter in the search box

Click HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/services/msahci


In msahci click start and change the ide value (3) to ahci (0)- save the registry and reboot. 

msahci ide mode

value ide = 3, ahci = 0

change value to 0 = ahci

Change Start in msahci from 3 to 0

Click DEL or F2 whichever the case may be while booting to enter bios – the options should be in “Integrated Peripherals” – Change all SATA controllers mode from IDE to AHCI.

select integrated peripherals

IDE function setup

change IDE to AHCI

all SATA modes are in AHCI

Hit F10 to save and exit, the windows will boot in AHCI mode very nicely without any problem.




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