Sounds like you've got the basics covered. If the drive is clicking during post attempts where it fails to post it could also be a power cable or a bad SATA cable.
Simple test.: shut it down. Open it and turn it on, listen for clicking. If present, turn if off again. unplug data cable from HD. Boot again. If gone, replace Sata cable. If not gone try different power lead from PSU. If power lead does not resolve, replace HD. (after you check for the sata port like you are already planning to do).