You have a pretty awesome chip actually. 4.5 at 1.224v is top of the line. (you are using cpuz to monitor volts right?)
Honestly, if it was my chip, I'd be popping the heat spreader off and running it bare silicon on water at the highest freq I could get (I'm thinking it might be a 5.0+ candidate).
But I don't mind having to replace broken parts on occasion, and past 4.5 doesn't make much difference in games anyway. So have fun with it.