Does it make a difference whether or not you turn your PC off at night?

leave it on and your using up your electricity, turn it off and your actually decreasing your computers life cycle as constant turning on and off can damage the hard drives arm

even though it is quite unnoticeable for a single end-user, the power or energy that is wasted will still be huge if it is combined worldwide. according to recent studies, 75% of the world's wasted electrical energy comes from hibernating or appliances on stand by. these include PCs, TVs, sound appliances.

it is a matter of opinion and what you use your computer for.

off for me is better-

you dont stress your fans (which has a lifespan of certain hour)

possible power surges or dips could damage HDD

Heat on your components

I could go on and give you quite a few reason, but it is better for your pocket and the environment to switch it off

I keep my computer on 24/7, I set it to check for virus and check for up date after 3 am.

You use more energy if you don't, obviously. You should restart sometimes, but you can leave it on overnight (just not connected to the internet). Otherwise, you better have a very good firewall.

computers today are build to stay running and shut down when needed (cpu fan died and over heating exc.) when you computer sleeps it uses almost no power i never shut and of our 3 computers off i dont see anything diffrent

if u put it in hibernation ur fine -- will only use bare min on power-- just set ur power up from ur mouse to power back up