Whether it's the computer, music system or the TV set, the modern home is permanently on standby, full of equipment that sits "half on", waiting to spring immediately to life when we ask it to.Windows XP no longer tells you when it is safe to shut down your computer. We sometimes leave our computers in Standby or Hibernation mode and forget to turn them off completely.
Shutting down using hibernate or standby is the same as leaving your computer on. A PC or any other hardware device like TV or printer is always using energy unless it is totally switched off.
According to BBC, a PC can consume power anywhere between five watts to 60 and beyond. If a million PC users switched to a more efficient power supply, it would save almost the equivalent of 250 million litres of gasoline a day.
PCMag adds that even if a PC is not being used, the monitor, printer, and various Ethernet and FireWire devices running and wasting energy. They suggest a modern power strip like the BiTS Smart Strip - When the computer stops drawing power, the Smart Strip senses it and automatically shuts off power to the other devices.
Related: Don't shut off your computer at night, just Hibernate
Energy cost of PCs on standby | Turn Off Peripherals At Shutdown