A computer has what I call a idle power usage, and a load power usage. Example your playing a game your PC is at load lets say its takeing 400 watts and you got a 500 watt PSU so for that time it uses 400 watts, but lets say you stop playing that game and are not doing anything and the mointor shuts off well you now using maybe 150 watts. I leave my computer on pretty darn near 24/7 without a hitch.