Well, you have exceeded Intels max voltage recomendation, but that's personal choice.
I've got mine running at 4.0 GHz (500X8) @1.280 Volts, 56 C Max.
The only thing I can say is your NB voltage is a little bit low for that FSB your running. I've needed 1.4 volts for mine to stabilize. Also you didn't mention anything about your ram and if it was overclocked.