Hi!
It's quite normal for a CPU to reach high temperatures during the stress test. The whole point of the test is to see how far it can go.
If you would like better cooling solution, think about investing into a more powerful cooler, either air or liquid.
IMHO, liquid is not worth it unless you are seriously into overclocking.
If you would like a recommendation for a good air cooler, I'd wholeheartedly recommend Noctua, but they are a bit on the expensive side.