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.
Sonnet has isolated the occurance of drives not mounting in 10.7.4, which occurs only in 32-bit mode with the Tempo SATA E4P, E4i, and Tempo SATA Pro ExpressCard/34. Users running in 64-bit mode will not experience any issue. (To boot in 64-bit, hold down the 6 and 4 keys when the Mac starts up.) Install driver 2.2.9 or greater to fix the 32-bit mode issue.
