reasons for high temps:
- dirty cabinet/CPU
Solution : Clean it..
- The air flow is blocked.. i.e. the CPU is in a closed space restricting the movement of hot air out and/or inlet of the cold air..
Solution : keep the CPU in an open place and test it..
- the CPU Fan is failing
Solution : get a new aftermarket cooler air/liquid
- Thermal paste will be automatically reapplied fresh when you get a new cooler..
70-80 C is normal under load/gaming..
40s is normal under light use..