did you check in BIOS if the controller was enabled or if it was set to operate as RAID? SATA controller SHOULD be ENABLED and RAID SHOULD be DISABLED
And if you plugged both the molex and the SATA power at the same time, you may have ruined the drive.
One more thing.. check on the drive if there is a jumper for SATA1/II operation. Try it at both position.