Asus 'default' bios settings for the KS are too agressive. Use LLC 3. AC LL .35, DC LL 1.1. This should drop temps at least 10C. Asus defaults are LLC3, AC=.60, DC=1.1.
Use OCCT AVX stress tests. If you don't pass use AC LL .40. If you pass and don't crash next go to VF Pt 5 (I believe) whatever VF pt is 5200mhz. Start with negative offset of .01 and stress test AVX in OCCT again. Keep going by .01 increments until crash then after crash move VF pt 'up' by .01. Mine is stable at a (-).05 offset using AVX. I've tested 4 KS's and every single one of them running at 'default' bios settings on my APEX would hit TJ max on a Cinebench run. You have got to undervolt as much as you can. Using CB_R23 (P52, E40 on the cores) My Vcore at load is 1.19v. Check what your Vcore at load is running CB_R23 using defaults. I bet it's near 1.3 or something crazy. You've got to 'tune' the KS. You can't just drop it in and run (Auto) on everything or you'll just have a great space heater.