Hence a missing cable. Yah - not fun. It's like how printer manufacturers stopped giving you a parallel cable many many years ago. And when they went to USB, many resisted throwing in a USB cable. Which was silly, since when anyone else sold you something USB, you get a cable.
If you'd bought the bits for DIY, I'm pretty sure the motherboard would have come with two SATA cables. My last one did.
Wade.