a lousy 12% gain in performance in 3d05 if your lucky enough to have a duel core cpu such as the fx-60
this lousy gain comes from the fact that 3DMark05 at default resolution is nearly completely CPU bound benchmark with CF. Its not because CF is "more CPU hungry" its because X1900CF has so much video speed that the CPU can't keep up with it at the default resolution.

So 3DMark05 with stock X1900CF and stock FX60 is basically just showing how fast the FX60 can run 3DMark05. If you overclock the X1900CF you dont see the score go up since its all CPU bound!

If you run 3DMark05 at some more relevant resolution such as 1600x1200 w/ 4AA and 8AF you see around 55%-60% improvement when you go from single X1900XTX to X1900 CF.