OS will start up with bios set to IDA but not with AHCI.
What I have tried: 1. installing the asus ahci driver at re-install of os. 2. changing registry values, e.g., changing start value to 0 in storahci.
From my understanding windows 7 and 8 (I am running 8 consumer preview) supports ahci and no driver from mb manufacture is needed. To activate ahci in win8 you change the storahci start value to 0 and then activate ahci in the bios. However, I am not getting results. Suggestions? Is there another registry value i need to change besides the storahci?
mb is: asus m4a88td-v evo/usb3

If your BIOS is set to run in IDE mode, as mine is, because I run XP in dual boot, the only way that I know of to get it to run in ACHI mode is to install the OS in that mode. I've done (or tried) some of those tricks using Windows 7 to run that were installed in ACHI mode in IDE mode, all BSOD'd on me.

What you need to do is go back into the BIOS & set it to ACHI mode & re-install, the install disk will pickup whatever mode you're running in. But if you're dual booting with another OS that's installed in IDE mode, then you'll be constantly having to switch the BIOS every time you want to boot into another OS.

Any particular reason you want to change? If you're running a mechanical (IDE or SATA) HDD, there will be no speed difference. I have a WD Caviar Black & 2 Samsung HD103SJ HDD's, no matter which mode they're in, the score is still the same (5.9 on Win 7).

It's my hope that I understood your question correctly, & hope that it solves your issue.

Best of Luck,
Cat