i use ppc on Virtex 4 FX60.
i don't know how much clock i can set for the processor.
when i set 200MHz for the clock, i can set the LEDs on the board, but by increasing the clock, i can't set LEDs. (cpu doesn't work).
in this link you can see dcm settings! in this setting i can set 315MHz for the PPC but it didn't run.