Energy efficiency is besides higher data rates a key to success of the next generation copper access technology, G.fast [1]. Power consumption targets are not only driven by government requirements, but also by the need for access nodes without local power supply, which are fed from the subscriber via reverse power feeding (RPF). G.fast introduces discontinuous operation (DO) to reduce power consumption by switching lines on and off on a short time scale. Implementing DO in combination with precoding requires to maintain precoding performance on active lines while other lines are discontinued. This paper investigates G.fast DO in combination with linear and nonlinear precoding. Spectrum and framing optimization for DO is discussed. Implementation approaches are compared in terms of complexity and power saving capabilities, considering realization aspects as well as standard-related limitations.