there are several diagnostic programs for hard drives. you can probably find a used drive tester on ebay. or check around with the computer repair dealers in your area. they may have an older one they would sell. some of the older ones will not support sata, sas or u320 scsi, 80 pin scsi or fibre.
you can use a tower to check drives, but you will have a lot of change out time involved.
you will want to use a good dod program to over write the drive. you can be held liable for information obtained from the drive.
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