- Windows 7 automatically installs the intel AHCI driver during installation if its enabled in the bios as you said - its the intel matrix storage manager that needs to be installed for full functionality - since Windows 7 installs the driver it wouldnt be showing in device manager as an unknown device, but I maybe misintrepreting this so moebiius
his the link to the matrix driver in detail, as I have it copied to a notepad for easy reply's - it will do no harm to download, and install it, as it wont install unless you have AHCI enabled.
You will find it at the intel site - http://downloadcenter.intel.com/default.aspx
Select chipsets - chipset software - intel(R) matrix storage manager - Select Operating System - select Windows 7 (64bit OR 32 bit) - select drivers - select intel(R) matrix storage manager 22.214.171.1243 - download and install.
(make sure you don't download the floppy configuration utility by mistake) - it will show up if you select utilities.