When upping Unigine Heaven to 2560 x 1600, it remained a tough race between the GTX 680 and HD 7950 when it was operating at its stock speeds. Overclocking the Radeon HD 7950 yielded a 21% boost in performance.
When running Xonotic at 1920 x 1080 with Ultimate image quality, the GeForce GTX 680 came out the winner -- even ahead of the overclocked Radeon HD 7950. However, when it came to running Xonotic at 2560 x 1600, the Radeon HD 7950 was the easy winner. This may be in part due to the Radeon HD 7950 packing 3GB of video RAM where as the GeForce GTX 680 only has 2GB of GDDR5 memory at hand.