The Adaptec SCSI Card 39320D is a dual-channel 64-bit, 133 MHz PCI-X SCSI card that delivers fast, reliable performance for enterprise servers and external storage using Ultra320 SCSI technology. The Adaptec SCSI Card 39320D powers your server with data transfer rates of up to 320 MByte/sec per channel for mainline storage, streaming video and audio, and other bandwidth-intensive applications. The Adaptec SCSI Card 39320D card incorporates packet protocol, the first protocol change to SCSI in 20 years, and Quick Arbitration and Selection (QAS). Packetized SCSI optimizes bus utilization and minimizes command overhead to bolster performance by transferring commands, data, and status using Dual Transition (DT) data phases instead of slower asynchronous phases. Packet protocol also allows multiple commands to be transferred in a single connection. QAS reduces the overhead of control release on the SCSI bus from one device to another to help decrease command overhead and increase bus utilization. Adaptec has extended its SCSI leadership and reputation for innovation with Seamless Streaming, a technology that optimizes Ultra320 SCSI performance by ensuring fast, smooth handling of data and command packets. Seamless Streaming sends multiple commands in a single connection, and allows up to 512 commands to be rapidly retrieved from its command management queue. It also allows a SCSI target, such as a disk drive, to stream packets of data for different commands with minimum switching time, maximizing Ultra320 SCSI data transfer rates. The Adaptec SCSI Card 39320D is designed for maximum configuration flexibility and ease of use. Ultra320 SCSI technology is compatible with Ultra160, Ultra2, Ultra Wide and all other previous-generation SCSI devices. The card's PCI-X interface enables host bus rates of over 1 GigaByte per second, making it possible to take full advantage of Ultra320 SCSI's doubled bandwidth. It is also backward compatible.