Set your screen-saver to 'none' or 'blank screen'
Despite the myth that screen savers save energy, screen savers are energy wasters. Most computers use about twice as much energy lighting up the screen as they use for processing. Originally, screen savers were designed to stop screens being burnt by a constant image, but they aren't needed for modern screens. Not only can screen savers use as much energy as a full screen of work, but many require considerable processing energy as well. genuineessays.com