Actually;
We have a brand new 8 core Mac pro with a new Kona LHi card and we expreniced the same thing running off of G-Raid FW800 drives. EX cam is not that data rate intensive, 35mbits a sec. At first I thought it was a drive problem but we use the same drives to edit on laptops and older Mac Pro’s. I concluded it was the Kona card but now I don’t know.