No you definitely should not be getting those temperatures. 70ºC at less than 20% load is not normal. At that load level with the stock cooler, you should be well below 50ºC, depending on ambient temperature. Is this your first time building a PC? If so, are you sure you mounted the stock cooler correctly? You have to push down all four pins until you hear a click, and then twist each of them 90º clockwise. You also need to have good airflow in order to have decent temperatures. Do you have any case fans? And what is the Vcore of your CPU idle and at 20% load? You can use CPU-Z to measure Vcore. DO NOT ATTEMPT TO STRESS TEST YOUR CPU. You'll only damage it unless your temperatures are back to normal.