Could you send me that vidcard of yours
Get a 2.4C from malaysia. And a P4C800. My P4P800 is good, but it won't allow for 1:1 over FSB 250MHz, though my whole setup can do 283MHz (ram and CPU). So I'm at 4:5. And the worst part is, I actually was able to enable PAT up to FSB250!!! But my northbridge is f* up, all P4P800 seem to be, and it shoots out all sort of errors over 250MHz at 1:1
With that 6800 and Northwood C, your PSU might also be limiting you.
No overvolting. Air cooling. Is there no way you can coax a 4:5 ratio from that memory of yours? To go over 333MHz, maybe you could slack mem latencies?