Some of NVIDIA's add-in board partners implemented the feature via a specialized fan controller chip but NVIDIA plans to incorporate the feature via its drivers, which will result in more flexibility as it will enable third-party GPU software makers (including the AIB partners) to create software that lets users control the feature based on their desires.
Given that its TITAN family of super high-end graphics cards never get to be custom-designed by AICs, NVIDIA has decided to standardize an idle fan-off feature of its own. Unlike AICs, who have used specialized fan-controller chips that take auxiliary temperature input to decide when to turn the fan off, NVIDIA's approach will be more driver-based. Future drivers accompanying the GTX TITAN X will offer a new feature, which when enabled, lets you choose between a non-linear fan curve that keeps the fan off; and one that runs it at low speeds. This should let the driver power the fan of a GTX TITAN X completely off, until it reaches a temperature threshold, and only then begin to ramp up speeds. It could help not just idle (desktop), but also light-gaming scenarios (think League of Legends).