The ARC-1680x SAS controller supports up to eight SAS ports using an 800 MHz Intel IOP348 I/O processor, 256MB of on-board DDR333 533 MHz SDRAM memory with ECC protection and an optimized RAID engine to support extreme RAID 6 performance.
http://www.amug.org/amug-web/html/am...s/areca/1680x/

performance results above indicate that an ARC-1680x using an eight drive Seagate 320GB 7200.10 in a RAID 5 configuration with the EnhanceBox E8-ML and an Apple Mac Pro can provide average read and write performance of over 400MB/sec.