The most powerful of Nvidia’s new GPUs—the GeForce GTX 880M and the GeForce GTX 870M—are based on Nvidia’s 28nm Kepler microarchitecture. Kepler also forms the basis of Nvidia’s most powerful desktop GPUs, including the GeForce GTX Titan Black. The GeForce GTX 850M is based on Nvidia’s newer 28nm microarchitecture, codenamed Maxwell.