I just bought an i5 7600K. Quick question.

[upraw_alex]

It says 3.8ghz but when I open core temp it says 4.2ghz.
Im on a Z270x ultra gaming , gigabyte

 

[connerweatherly17]

That's the intel turbo technology, the base clock is 3.8 ghz and the turbo clock is 4.2, its fine

 

[manddy123]

To back the comment above up, see this:
https://ark.intel.com/products/97144/Intel-Core-i5-7600K-Processor-6M-Cache-up-to-4_20-GHz

He's refering to the Base vs. Max Turbo frequency