I have an Abit AB9 QuadGT motherboard and am trying to swap over to AHCI mode.
I have an existing Windows 7 installation which was installed under IDE mode.
I have set the msahci registry setting to 0.
When I try to boot in AHCI mode I get "DISK BOOT FAILURE, INSERT SYSTEM DISK AND PRESS ENTER".
I have tried booting with my Win 7 DVD in the optical drive.
There is 1 SSD (System), 1 HDD (Data) and 2 optical drives connected via SATA
If I switch back to IDE mode everything boots fine, either from the SSD or from a CD or DVD in the optical drive.
Why can't I use AHCI mode?
UPDATE: June 2012 - After buying 2 new faster SSD drives I had another go at this. I discovered I had a buggy BIOS version and a later version fixed the AHCI issue. Abit went out of business in 2009 so for anyone who is still using one of these boards and has the same issue, I include a link here to the page where I found the later BIOS: