SCA drives are best utilized in SCSI RAID configurations with hot-swappable backplanes. The device ID, power, and data bus are all in the 80-pin connector. Device ID is set at the backplane (via hardware or BIOS; SCA drives generally don't have ID jumpers). These drives aren't great for desktop PCs with SCSI cards in them, because you will also have to buy an adapter for the SCA drive that will allow you to connect it to a 50 or 68-pin SCSI cable. The adapter will also have device ID jumpers, power connection, and, if you buy a more expensive adapter, the ability to terminate the SCSI chain. An SCA adapter will probably cost over $20 for a good one.