You need to bee more specific... Max core temperature refers to Tjunction Max, which is the temperature your processor will start to throttle down in order to avoid damage, somewhere around 100c. Your more than likely talking about max "safe" core temperature, which is in fact around 70c.
For 24/7 operation, I would recommend keeping under 60c-65c. Benchmark/stress test to 75 is ok. Other than that, your good to go.