I have had my new G5 5590 for 2 days now and have noticed that when its plugged into AC and charging the CPU temperature jumps ups by 20°C the instant I plug it in and then it fluctuates between 65°C to 80°C when just idling, however when I switch the AC power to battery the temperature quickly drops down to 45-55°C and stays there.
Any idea what this could be? A fault battery?
This might be due to the background process that are running. You can shut down such background running apps. Temp of 60-80% is normal. Unless it is 90-100 you dont need to worry about it.
Still i would advise you to Run a hardware diagnostic