My mobo has this option, and I've hit a wall around 2.8ghz (10x280) that runs stable. Heat is not an issue at the moment, so I can rule that out. I've tried 9x333 and 10x300 to get to 3.0ghz. It's not a big deal, but I was wondering if OCing the FSB would potentially help, or if the chip has hit its limits.