There are several issues here:
1) To answer your question, any temperature is safe. If it gets too hot, the cpu will downclock, or shut off to protect itself.
2) Is your temperature reading accurate? You might confirm your readings by using realtemp of speedfan.
3) What is the ambient temperature of your room? A cpu cooler can only cool to some number above the ambient. That might be 15c for idle, and 45c at load.
If your room is 25c(77f.) then your temperatures are too hot, and there is some sort of a problem.
4) What liquid cooler do you have? Is the cooler seated properly? Did you use too much grease?
5) What case do you have? You can tell if your case is the problem by ttaking the side doors off, and directing a house fan at the innards. If the temperatures drop significantly, then you have a case cooling problem.
6) Have you increased the cpu voltage significantly? If so, that is why your temperatures are high, and overvolting can be unsafe in the long run. A modest 10% overclock should not require a voltage change. Just raise the BCLK and leave the voltage and ram on AUTO.