Depends on what you are doing. If you are not doing very much, then this is not good. If you are gaming heavily, then this is normal. Your environment also matters. Is your machine dusty? Is your room cool and well-ventilated? Many factors to consider here.
Graphics cards are typically built to withstand 100°C+ for short period of time. I've ran a few at 90°C+ for years with no problem. But you know you are doing something out of your card's league when temperature starts hitting ~80°C.