The GTX 260 was build on a 65 nm process, the 960 on a 28 nm process. This is one and a half full nodes apart, on similar planar processes with a full node real

The GTX 260 was build on a 65 nm process, the 960 on a 28 nm process. This is one and a half full nodes apart, on similar planar processes with a full node really was a doubling of density. While the transistor count increased by more than that (1.4B to 5.2B), leading to a larger die size, it can't be overstated how much the improved process and decreased Vth helped power usage in this era. It would have been a challenge to use more power across those processes.