GPU Boost is a term Nvidia coined to describe leveraging all of a GPU's (aka graphics card's aka video card's) potential power to maximize a display’s frame rate while you’re gaming.
In Nvidia’s own words: “Starting with our GTX 600 series and later, every application and game runs at a guaranteed, minimum base clock speed. If there’s extra power available, a Boost Clock is enabled, increasing clock speedsuntil the graphics card hits its predetermined Power Target. This dynamic clock speed adjustment is controlled by GPU Boost, which monitors a raft of data and makes real-time changes to speeds and voltages several times per second, maximizing performance in each and every application.”
This article is part of the Tom's Hardware Glossary.