I ran into the cable issue, too. Switching the drives and cables made it work, now. When I read the trouble some of you had, I thought that I had a different issue I had.
I just updated the Mac Mini 2012 i7 2,3 Ghz. I wanted to add the Samsung 840 Pro to the existing 1TB drive and have Windows 8 on the SSD via bootcamp and Mac OS on the original drive. Adding the SSD as additional drive with the ifixit cable worked well at first, but I was not able to get Windows or Mac OS to boot from the SSD, no matter what. Windows started installation alright, but could never survive the first reboot in install. For Windows 7 and 8 it showed "Disk Read Error". I tried all kinds of partitionings, I tried copying Mac OS via CCC - nothing was able to boot. The SSD worked fine and I got no errors other than when trying to make it bootable.
When I switched the drives, so that the Apple HD used the new cable and the SSD the old one, I was able to install and boot from Windows just fine. Booting into Mac OS from the original drive works as well.
Greetings from Bavaria!