Your cooler is a minimum capability unit.
94c. is about as hot as you want to be.
You likely need a better cooler.
What is your case?
With a good case you will have many options.
as of 3/22/2018
What % of I5-8600k chips can oc
at a aggressive vcore of 1.4 or so and delidded
4.9 96%
5.0 85%
5.1 66%
5.2 38%
5.3 13%
Note the delidded caveat. About $50 to have it done professionally.
Usually, the vcore @1.4 will be the limit as to what you can safely do.
I run a delidded 8600K @5.0 with no issues as to heat.
I use a noctua NH-D15s in a silverstone TJ-08E case.