I5 11600k thermal throttling

[Brawur]

Hello,

I have a strange „problem” with thermal throttling of 11600k during OCCT CPU-focused stress test.
It goes up to 80+ celsius in first seconds of test, then after 1 min its 88/90 and approx after 1:30min when it hits 92/93 it starts to throttle.
Frequency, Volts and Watts is dropping and raising, temps starts to oscilate 70-90 celsius.
I have Endorfy FERA 5 single radiator and checked twice the thermal paste (savio glacier TG-3)
Mobo: gigabyte b560m ds3h

In gaming obviously cpu is oscilating between 60-75 celsius but I would like to have stable CPU in every situation.
Should I undervolt it? And how to properly do it on this mobo?

[Brawur]

I changed cooling for deepcool AK620 and problem is gone, CPU temps under heavy stress etc. dropped at least 10 celsius.

With low-end cooler undervolting did the job, but with proper cooling system now there is no need to undervolt. Temperature doesn't go beyond 83 celsius in aida, occt.