Hy Grantly, i do experience the same problem. I am actually configured exactly as you are, except 8 gig of RAM. FCP always report dropped frames when my K3 is active. I just uninstall K3 and everything seems to be fine.
FB card in slot 4
K3 slot 3
Empty slot 2
Radeon slot 1
Expansion slot option 2
4 – x4
3 – x4
2 – x1
1 – x16
I already had all the latest drivers, I just reinstall Kona 3 drivers and Had the same problem.
I had another system with a Kona 3, I just swap the two K3 cards between the 2 machine … I’m experiancing the same problem. Now I really don’t know what to do.
If anyone can help …
Jeff