Ive had mine up to 1700 FSB ( 425 ) but as said it takes a bit of time to fiddle with it to get it stable.
Just be sure to use the latest BIOS. I found that the biggest cause of instability is running the RAM unlinked, as i wanted to run it at its full 1066Mhz but this resulted in bluescreens and freezes, even with the correct voltage. But running it in Linked Sync mode its rock solid.
All voltages are on auto apart from CPU and memory.