GeForce GTX 770 DirectCU II 4GB OC Edition is a special edition of the high-end GeForce GTX 770.
This edition comes with a custom cooling solution, 20% cooler and 3X quieter, which by itself should allow a slight performance boost, as GeForce GTX 770 benefits from the GPU Boost 2.0 technology.
Also, it has been overclocked out of the box from 1046MHz to 1058MHz while its boost clock is now of 1110MHz. The memory clock was left untouched.
Furthermore, the frame buffer was doubled to 4GB though this will not boost its performance and can be addressed as a gimmick - marketing to lure consumers into paying more for the same product.
Benchmarks indicate a 4% performance boost when compared to the reference card and so this edition performs very slightly better than GeForce GTX 590.