i've got a 2.4c @ 3.3 ghz ( 275mhz 1:1) and my 9800pro at 455/376 with NO problems and no voltmods. I'm watercooled too....but funny thing is that i could run it at 475 stable in 3dmark and far cry but i get white dots everywhere that high so i had to back it down to 450'ish to run right....strange, but still a good overclock.