FWIW, I've tried it a few different ways, from leaving everything on all the time, to plugging the PC and all peripherals into one surge protector, shutting down and then hitting the kill switch on the surge protector, to what I do now: shut down the PC and turn off the monitor at night, leaving the modem and router running. My electric bill did seem a few dollars higher when the PC was running all the time, but I see no difference between cutting power to everything and simply turning off the monitor and PC.