Spread Spectrum Clocking is a way to lower electromagnetic interference or EMI. This is important for storage solutions that are required to pass FCC and other agency certifications. All current Serial ATA disk drives implement SSC (some allow you to turn this feature on/off). However, some older SATA drives do not implement SSC. All Sonnet Serial ATA host adapter cards support SSC but will also work with disk drives that do not.
Our testing has shown that a four-drive array will sustain maximum reads and writes of about 200 MB/second in a 64bit, 33MHz PCI slot. An eight-drive array will not provide any additional performance beyond that of a four-drive array in that slot. To get significantly more performance, you need to use a machine with a PCI-X slot.