I have an early 2008 Mac Pro and have two hard drives in it. The main system drive is a 2TB Western Digital drive I installed about a year ago. The 2nd drive is a 1TB Seagate drive which is the original drive that came with the Mac Pro. When looking at Disk Utility a few days ago I realized the drive is showing up in Red and it's saying that SMART is failing. I've never had this happen before and like having a warning. First Question: When SMART shows up as failing can it be a false alarm or is it likely a definite sign of impending hard drive failure? When this happens, does the drive frequently fail quickly or does it take awhile? The fortunate thing is I back this drive up frequently to Time Machine. Second Question: What SATA speed does the Mac Pro handle? I see many hard drives that are 3.0GB/s and some that are 6.0GB/s. Does the Mac Pro handle the faster 6.0GB/s? If not, would they still work but just not at the additional speed? I may consider upgrading to a 1.5TB or 2TB but figured I'll go with a Western Digital or Seagate drive. I see cache ranging from 16MB to 64MB and speeds at 5400RPM and 7200RPM. Between these two which is more important, large cache size or RPM's? Thank you for your help.