A short explanation for those who don't know what the difference is between the 9900K and 9900KS. The 9900KS is basically the exact same processor as the 9900K with the difference that Intel "guarantees" that it can clock at 5 GHZ on all cores which only about 40% of the 9900K can do (stable). They simply took a Silicon lottery 9900K, screwed the wattage to 127 and did a factory overclock. But it is not guaranteed that it can clock much higher than 5.ghz. It is simply a binned version of the K which has a factory overclock. The thermals are accordingly higher as it clocks higher and sucks more watts. With a fan cooler I wouldn't recommend it unless it is a very good cooler as the processor can reach 109 degrees on air at max load. a little tip there is a site called Silicon lottery that sells 9900K which can also do 5 GHz on all cores by the way.