Assuming your cooling solution is okay, then the temperature of the CPU shouldn’t matter – it will work as specified within the specified temperature range. That’s how it’s designed. Be happy that you have many cores that can compile shaders for you.
If your cooling solution is not okay, then the problem really is the cooling solution, not the programs you run on your CPU. The work needs to be done, no matter what …
If you still want to run slower and cooler for some reason, you might be able to turn off SMT, and perhaps turn off frequency boost, in the BIOS, even if you can’t set a different temperature threshold. This will cause the CPU to work less hard, and thus generate less heat. Whether that will cram you in under the temperature limit you want, you’d have to test to find out. Worst case, keep under-clocking.