I just bought a Dell Inspiron 530 that came with 2 SATA drives (Samsung Spinpoint) in a non-RAID config. According to the chipset (G33 and ICH9R) AHCI and NCQ are supported but to my surprise the BIOS only has the two options IDE and RAID, no AHCI.
Tech support told me that choosing IDE would still use the AHCI capability of the controller but after installing XP successfully without any supplementary SATA drivers (and seeing atapi.sys being loaded for my controller in device manager) I seriously have my doubts. I even did a second install of XP using a slipstreamed installation CD including the ICH9R AHCI driver to double check but the result was the same (atapi.sys used for the controller).
I still want to use AHCI in a non-RAID setup as it's technically possible and would give better performance. Are there any steps I could undertake, e.g. switching RAID on in the BIOS and just not setup any RAID volumes? (As far as I understand the controller implicitly uses AHCI when RAID is enabled.) I rather ask first before messing up the data on my 2nd HDD...