The official word for ATA (IDE) drives is.. the MASTER must be on the end of the cable. The SLAVE, if present, goes in the middle of the cable, unless it is the only drive (no MASTER).

40/80 wire cables don't change that. However, 80W is required to utilize transfer speeds faster than 33MB/sec (the cable type is detected in s/w, and fast speeds are disabled if an 80W cable is not found), and 80W generally improves reliability in marginal setups.

-ml