One possible limit is the short turbo time - if the CPU is loaded continuously, the short turbo time expires in probably about half a minute. After that, PL1 throttling kicks in, restricting the power to the nominal TDP of 45W, which presumably allows about 3.1 GHz with all cores loaded (you can try the Prime95 load test with 12 threads or less). Some programs load the CPU intermittently and don‘t get tripped by this.