Bios settings / adding 2nd HD to a T3500

I want to add a 2nd sata hard drive to my precision T3500 running Win 7
64-bit - in a non raid configuration. It currently has 1 hard drive
(sata 0) and dvd (sata 2), but I've hit a bump.

Even though I ordered the "non-raid" configuration from Dell, the "sata
operation" section of the system bios (A08) has the "Raid on" option
set, even though there is currently only 1 hard drive. There are two
other options avialable: "raid autodetect / ahci" and "raid autodetect
/ ata". None of the documentation I've found gives any detail about the
bios settings for raid/non-raid, and I'm lost for what would be the
proper setting for a non-raid setup. I'm assuming that it's not:
"Raid on" where it's currently set. Also, I get a warning that
changing these bios settings may make the system unable to boot and
would need to reinstall the OS.

Does anyone know what bios setting(s) would be correct for a non-raid
operation, and how likely it is that changing this setting would cause
me to have to reinstall windows?

Thanks,

Bill
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