I own a DELL Optiplex 745 Mini Tower with 160 Gb SATA Hard drive. I attempted to add a second 160Gb SATA Hard drive. I connected the extra power supply to the second drive. I then connected a SATA data cable to the hard drive with the other end plugged in to a slot on the motherboard. I then booted my computer. However, the computer cannot see the second hard drive. Is there any other thing which I should have done? Thanks for your advice.