Hello,
In this scenario, all drives work when connected to the PSU. As long as the molex power cable from the PSU is plugged into the Hard Drive, it is drawing power. This negates the idea of there not being enough power from the PSU.
I suspect a faulty IDE cable or motherboard grounding.
Try using a different IDE cable to connected the hard drive to the motherboard. Also make sure that the motherboard is not grounded to the case (by ensuring that metal contacts on the motherboard do not touch the interior of the computer case if it is metal). When fixing the motherboard to the case, the motherboard should be raised above the internal surface of the case (using standoffs on the screw mounts).