A04: Leave computer on or shut down
QUESTION: Should I leave my computer on or shut it down at the end of the day?
ANSWER: Ah, the great debate—there are valid arguments on both sides. The "keep it on" folks argue that every time you turn the computer off and on tiny bits of information never make it back to their original place and this eventually slows things down. Alternatively, the "turn it off" folks believe that the computer generates heat and should not be left on indefinitely. In other words, it should be given a rest and it is a waste of energy to leave it on.
Here’s my advice. A laptop computer by virtue of its small size should definitely not be left on indefinitely. This is because air doesn’t get a chance to circulate around a laptop as it does with a desktop and the heat that it generates can eventually be harmful. I turn my laptop off if I’m not going to be using it in the next hour. But, it is ultimately your call. Feel the underside of your laptop and see if it’s hot after it has sat for a bit. If you have a desktop, go with whatever makes you comfortable. I know many people who turn their computers off when they’re not in use and I have yet to hear that any damage has been done. Always turn your computer off during electrical storms.