Apple uses Nvidias GPU Kepler-class architecture video cards.

With Apple’s slim new 21.5- and 27-inch iMacs, NVIDIA used the Kepler-class architecture in order to design Slim and powerful GPUs apropriate for the "Video rendering" part.

According to Nvidia, based on the new Kepler-class architecture, helps make GPUs up to 60 percent faster than last year’s models.

So the new 27-inch iMac comes with the GeForce GTX 660M as its base GPU, or the even faster GeForce GTX 675MX or also the GeForce GTX 680MX. The 21.5-inch model comes with the GeForce GT 640M GPU, with an available upgrade to the GeForce GT 650M GPU.

As Apple is synonymous with top-performance and high-quality products, it’s no coincidence that the new iMac uses GeForce. Kepler’s unprecedented performance and incredible power efficiency will make iMac an ideal pc to pursue.