: Indicates support for Intel's 64-bit instruction set, allowing the system to address more than 4GB of RAM and run 64-bit applications natively.
The "K" suffix means unlocked. The 6700K was a decent overclocker, often hitting 4.6GHz to 4.8GHz with a good cooler. However, the 14nm early yields could run hot and voltage scaling was often poor (requiring high voltage for small gains). Still, a 4.7GHz overclock can help squeeze a few extra frames out of modern games.
Identity: Intel64 Family 6 Model 94
Here’s a full technical review of the processor.