Since I don't use AMD chips, I cannot speak from experience. However, if the Tj Max shown of 85c is accurate for that chip I would guess that 60c is the highest you'd want to go under full 100% load.
With Intel processors, a rule of thumb is approx. 70% pf Tj Max.
Of course the best way to find out is just go to AMD's website, and look up the thermal specs for the Phenom II 1045T.