Maybe your block isn't level? Do you have TX-2 applied?
With those temps I would think that you could take her further. Of course I think you are getting into the realm of mobo limits. I don't know what your board is good for, but I know mine is capable of 700mhz. I never took it that high since my e7200 maxed out well before that.
Try lowering you ram to below stock settings and cranking the NB voltage. I would also point a fan that the NB, that should help. This is getting very exciting.