A 2006 Mac Pro uses SATA-1, however the SAS drives will run at Sata-2 speed 3Gb/sec. Buy a SAS PCI-Express Raid card and put it in slot 1 or 4 and configure 16 lanes. Then buy a SAS-Sata cable. Remove the old Sata cable from the logic board. Connect the new SAS-Sata cable to the logic board. If you don't have SATA-2 or 3 hard drives buy four. Now you are running SATA-2 or 3 at 3Gb/sec through the backplane. I configured mine for RAID-10. Next connect two SSD's to the hidden Sata Ports on the logic board behind the fan. Install Lion on either one of the SSD's or run the two striped. Congratulations, you now have your OS on an SSD, and you are running your four SATA-2 or3 drives at full speed, 3Gb/sec. You just took your 2006 Mac Pro up about four years. Check out my attachments.