You'd think we'd have been able to come to a consensus on this by now:
If you're the PC guy in the family or some other group, you've probably been asked this question: "At night should I turn my computer off?"Ever since normal people have had computers, this question has made the rounds with a variety of "expert" answers. The early versions presented a trade-off between power consumption and stress on components. Turning the computer on or off, so the theory goes and accurately I believe, is the most physically stressful thing you do to it all day, so I think most experts have advised that it's better to leave the system on.
But in the age of the Internet, and especially in the age of broadband connections, there's a new angle probably more significant in the average case than all that wear and tear stuff. Some would claim that if you have one of those "newfangled" always-on broadband connections, then you're exposing your PC to more attacks than if you were to shut it off during periods of disuse.
In my early years of PC use, long before my junior year of college and first broadband connection, the computer was shut off after every session. I was not connected senior year - I can't quite remember, but considering I lived in a rickety old house with six mates of similarly humble means, I probably shut the computer off. I joined the 24-7 club and remained in for the next three years on the grounds that, as Larry Seltzer explains here, my computer experienced more stress when shut down and power back up. But after moving into my apartment and paying three of what I considered to be exorbitant electricity bills last summer, I decided to put the place into lockdown whenever I went away. I prefer open windows, so I didn't touch the air conditioner once; but I kept the apartment's living room ceiling fan on its highest setting nearly all the time. Before leaving the apartment, my two computers were turned off and the ceiling fan set to its lowest setting or switched off completely.
My bills are currently half the size of those from the summer - the first one to arrive that way came in September, immediately after my decision. My change of habits wasn't a perfectly controlled experiment, but a few conversations reveal that my fan wouldn't necessarily be a resource hog. Besides, the accumulated savings of a few hundred dollars is worth a layman's disagreement with Mr. Seltzer; and I leave server applications to the professionals. When I'm done with the box, "Shut Down" is Windows' best friend.