hmmm, well this is my first post here.
Also running a 4coredual-sataII. Got it running @300 with an E4400, no BSEL, and 2x512M DDR (PC3200)@225(4:3). Graphics is a XT800GT@500/500 AGP
For me the solution getting this board stable @ 300 was resetting the bios and then loading optimal bios...