PC Drives not being detected?

Just finished building my second ever PC. The first one was O.K. This one is a little more advanced with a Gigabyte M/B, 1 SATA H/D & 1 SATA DVD. Going into BIOS I find that neither drives are recognized. I can change the 'none' selection to 'auto' & select 'auto-detect' but it makes no difference. Any ideas?