I have a P8B75-M LX MB. I already have a sata6G drive, wanted to add a 6g SSD. Unfortunately only 1 6g port. Anyway it seemed from what I read, I could plug it into one of the sata3g ports (using a 6g cable - pins should be the same?) - but then the pc won't boot. unplug it and boots fine. I tried a couple different 3g ports, no change. What don't I know please?