Usually, yes, you can use the SATA RAID ports as regular SATA ports. On my
mobo, I have to create a RAID 0 volume consisting of just a single drive. If
I want, I can have 4 single disk RAID volumes, which is basically what a
standard SATA controller does.
Note: Some RAID controllers have a setting for JBOD (Just a Bunch Of Disks)
which uses no RAID settings and each disk is independent.
Also, I have not tried to move a SATA disk from a regular SATA controller to
a SATA RAID controller, so hopefully someone else has some experience with