One of the new features of the Intel Core i9 laptop processors is Intel Thermal Velocity Boost.
The Core i9-8950HK is the first mobile Core i9, it's a six-core, twelve-threaded processor with a 45W TDP, a 2.9GHz base clock and 12MB cache. The multiplier is unlocked and the chip has a 4.6GHz Boost. The new Thermal Velocity Boost enables the 8950HK to hit a single-core frequency of 4.8GHz, as long as the chip's temperature stays below 53°C. Under multi-core loads, the maximum Thermal Velocity Boost is 4.7GHz.
Basically, the new feature encourages laptop makers to beef up the cooling.