Some people would say that you can keep putting your processor volts up t as long as your cooling can accomodate the extra heat produced. Ultimately you have to decide how important it is for you not to destroy your processor. I had a quick look around google and the thermal specification temp for that chip is 63 celsius, i think. So dont go over that, in fact I would stay under 50 but that still gives you 10 degrees to play with. As for how many volts, all I can tell you is that my chip the e6850 is meant for 1.35 max and its nearly 1.5v on my board and this is were I bottle it cause I dont want to break it although it would probably go much further.
Hope it helps
