Do you mean SCSI cables or is it IDE?
I would get a new drive for the O/S and then check out the 'failed' drive afterwards. Or use the data drive in another computer to access.
When you say failed, what messages (if any) are you getting.
I have one old computer (IBM 1996) which often gives 'no system disk' and it always responds to re-seating the card (mobo connection broken so using PCI IDE card) or re-connecting IDE or power cables.