What is a SCSI Card?

R. Kayne

SCSI (pronounced scuzzy) is short for Small Computer System Interface, and the SCSI card controls various SCSI devices. SCSI devices might be hard drives, optical drives, scanners or tape drives.

A Small Computer System Interface (SCSI) card is a computer component that controls various devices such as hard drives and scanners.
A Small Computer System Interface (SCSI) card is a computer component that controls various devices such as hard drives and scanners.

A SCSI card is inserted into a PCI slot inside the computer. SCSI is a competing technology to the more standard IDE (Integrated Drive Electronics). Most hard disks are IDE, but the IDE controller card is integrated into the motherboard. If SCSI components are desired, a SCSI card is required.

There are various versions of the SCSI card that feature different connectors as the technology has evolved.

  • 25-pin card controls original SCSI devices
  • 50-pin card controls Narrow (8-bit) SCSI-2, FastSCSI, and Ultra SCSI devices
  • 68-pin card controls Wide (16-bit) Ultra-Wide, Ultra2, Ultra 160, and Ultra 320 devices

Many people prefer SCSI to standard IDE as SCSI technology is much faster. SCSI drives are popular in servers and among power users. A SCSI card has its own processing chip and does not need to rely on the CPU (Central Processing Unit). The trade-off is that SCSI devices are more expensive than IDE devices. For this reason, many people opt to buy and use IDE hard drives, but will install a SCSI card for a SCSI DVD burner. The added speed of SCSI is useful for the demanding needs of burning and playing CDs and DVDs.

A great advantage of this type of card is that it can link up to 15 devices per card. This configuration is called daisy chaining and each device on the SCSI cable is assigned its own ID. The ability to add on to the SCSI card provides great flexibility for a RAID (Redundant Array of Independent Disks). If considering SCSI for a RAID, another viable alternative is a SATA (Serial ATA) RAID. SATA hard drives will be less expensive than SCSI drives, and the latest SATA drives should be comparable in speed to a SCSI Ultra 160 RAID or better.

SCSI cards are available everywhere computer components are sold. When purchasing one, be sure it is compatible with the SCSI components you wish to purchase. SCSI devices generally carry a longer warranty than IDE devices, and SCSI drives are designed to work 24/7, catering to the server market.

You might also Like

Discussion Comments


@Charred - Another standard to consider is the SATA card (Serial Advanced Technology Attachment) which lets you hook up hard drives and optical drives with ease. It has “hot swapping” so you can change your hardware configuration easily, and it uses a serial cable to transfer the data transfer rate at blazing fast speed compared to the older technologies.


@nony - Yes, and if you’re looking into building servers, you might want to look into the Ultra320 SCSI card. It’s super fast, backward compatible with a lot of the older SCSI standards and is pretty much plug and play without having to mess too much with jumper settings.


@allenJo - Frankly, SCSI hard drives have a lot of things going for them, but storage is not one of them. You pay a premium for the storage with a SCSI controller based hard drive than you would with a competing IDE drive.

It is speed, and not storage, that would determine if SCSI is appropriate for any application. Servers use SCSI because they need the speed; they need to respond quickly to user requests. If you’re doing video editing, you’re better off staying with IDE.


I do a lot of video editing. Would a SCSI hard drive be appropriate for my purposes or should I stick with an IDE hard drive?


pl. inform me whether by using SCSI card 10 cd can be write at a time in same computer? for this what will be the specification of the computer? what type of CD writer will be used?

with regards

dipanka goswami

Post your comments
Forgot password?