it's the cooler's fault it just doesn't cut it and won't be able to transfer the heat quick enough while under load unfortunately. The only way to solve this would be to get a new cooler unfortunately. But now thinking of it for the meanwhile you could just crank for fans to the max in your bios settings by adjusting your fan curve, just remember that this will just get you by until you get a new cooler and is not meant as a permanent solution.