I have this Processor too, but with a biostar TA790gx a3+ mobo. I can't get the clock past 240. I tried increasing he voltage, but windows refuses to boot. Is there something I'm missing? all I adjust is the CPU voltage and the clock. do I need to adjust anything else?
Try reducing your hypertransport multiplier, your north bridge multiplier or your ram multiplier to bring each as close to stock speed as possible.