Hi,
your temps do sound excessive, I did check what your cpu tops out at and it is 100c so your close to the max.
Possible causes?
Your voltage sounds way too high and probably is the cause of all the heat.
Apparently your chip should average 1.34v, I got that info from 'Reddit':
Average 9900ks sit around 1.34-1.36v on most boards, and around 1.27-1.30v on ASUS boards for 5Ghz, with "bad" 9900ks being anything above those levels.
The information is in a reply to the question above.
Any thoughts on how to fix this?
See if the bios update helps otherwise you can manually change the voltage yourself via the bios settings.
If you need help with this let me know.