[ The PC Guide | Systems and Components Reference Guide | Hard Disk Drives | Hard Disk Interfaces and Configuration | IDE/ATA vs. SCSI: Interface Comparison ]

In terms of cost, the IDE/ATA interface is superior to the SCSI interface in virtually every way. The only exception would be if you needed to use, say, 10 devices, in which case SCSI might be cheaper because this would require a special solution to do in IDE/ATA. I am assuming that nobody would use IDE/ATA for that many drives anyway.

Here are four specific reasons why SCSI is more expensive than IDE/ATA (there are probably others as well):

• Additional Hardware: SCSI setups require a host adapter, which means either an add-in card or a more expensive motherboard. Cables, terminators and adapters also add to the cost of most SCSI implementations.
• Lower Volume: Far fewer SCSI devices are sold than IDE/ATA devices. The price of an item manufactured in high volume is usually less than one manufactured in low volume.
• Niche Market: Since SCSI has a reputation for being higher-performance and is generally used by those who are less cost sensitive, sellers can afford to run higher margins and still make the sale, and will usually do so. People are willing to pay more for SCSI, and SCSI costs more because of this.
• More Advanced Technology: This is really a matter of appearances: since the performance-conscious use SCSI, it is the interface where the most advanced new drives will typically show up first. Newer and faster technology is more expensive than older and slower technology. The price gap between the cost of SCSI and IDE/ATA drives has actually increased over the last few years. Just remember that comparing a "36 GB IDE drive" to a "36 GB SCSI drive" is making an apples-and-oranges comparison, because the SCSI drive is almost certain to offer much more performance, and for reasons that have nothing to do with the interface.

For those for whom cost is an important consideration, IDE/ATA will win over SCSI virtually every time. For low-end systems, the extra funds required to go to SCSI will usually be better spent upgrading core parts of the system such as the processor or system RAM. This is important to remember: those building performance systems should make sure they have addressed proper component balance and adequate system memory and other key components before making the jump to SCSI.

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