on an intel system.. anything over 70C and you might want to start worrying.. but with insane overclocks and pushing a lot of FSB and memory bandwidth.. high 50-60C isnt to uncommon..
I can't remember 100% but I believe I remember reading it was 103C for Tc-MAX. And just for reference mine is at 29C after about 10 hours of prime, same after 20 passes with IBT, no fan on a P5Q-Pro, stock HS.