Always On?

IEEE Spectrum Magazine, Jan. 2000

Do you leave your home PC on when you're not using it?  About half of the people that I've asked have said that they do.  For myself, though, I can't do it.  Some lessons that you learn from your parents stick with you throughout your life, and turning off electrical appliances when they're not being used is one such lesson for me.

I remember arguing with my father about the economics of turning off lights.  I think that back then leaving a light on overnight probably cost a penny or so.  I contended that the light bulbs would last longer if they were left on, and that the savings in light bulb cost would offset the extra electricity cost.  I don't think that I really believed that myself, rather I was simply trying to excuse my laziness in failing to turn off lights.

Needless to say, this argument did not save me from light switch duty.  I don't remember my father actually engaging the logic.  "Turn the lights off," would be his only response to my argument.  Many years later, the irony would be that I would tell my children the same thing.  "Turn the lights off," I would invariably say.  Even to this day, I roam the house at night, seeking lights that have been left on, as if this were the most important task in the world.  Alas, such is the cycle of life.

So I have this deep psychological thing where I have to turn off my PC when I'm not using it.  I just can't leave it humming away unattended.  I don't think my problem is the cost of the electricity.  Instead I imagine the rainforests that I am depleting.  I worry about the phosphors on the screen burning out.  I think about all those circuits being needlessly clocked hundreds of millions of times per second, and I worry they will become tired and wear out.  Most of all, though, I worry about the hard drive spinning away.  I listen to its whir, and I get the belief that it is on the brink of some fatal crash that will eliminate all of my precious files.  I just can't let this happen.  The PC must be turned off.

That's the psychology, but what is the logic?  First, I realize that I could make the monitor time out and maybe the disk drive too.  But I turned those timers off when they started to deactivate things when I was actually sitting in front of the PC.  There's something particularly aggravating about a PC turning stuff off on you, like it's going off in a pout because you're not giving it your attention.  Laptops, of course, are much worse.  When I'm working on battery, mine wants to go to sleep abruptly at the most inopportune times.  I consider its behavior very unfriendly.

Then, too, I'm very conscious of the fact that when I turn off my PC, it is going to take forever to boot up again.  This is something else that I don't understand.  We have processor chips with clock rates approaching a gigaHertz, but it takes a half hour to boot a PC.  Why is this, and why isn't someone doing something about it?  Moreover, in recent years the operating systems won't even let you turn them off without a significant delay.  Someone was complaining to me recently that he almost missed an airplane, because after the security people asked him to turn on his PC, he had to endure the interminable delay for shutdown.  Why can't these systems continually update their state in some non-volatile memory, so they can be turned on and off like everything else in the world?  I'm obviously missing something, and I have the feeling that a lot of people are going to be telling me what that something is.

Now about the monitor -- is it really true that the phosphors are going to burn out unless the screen keeps changing?  I mean, have you ever heard of someone actually burning out phosphors on their screen, or is this just a big plot to sell screensavers?  Has someone actually calculated how long phosphors last, and how long the average person actually keeps a given monitor?  The way the industry works is that larger and better monitors keep getting cheaper than the one you have, so every few years you replace your monitor anyway, regardless of the condition of the phosphors.  Meanwhile, I am staring at my screen at this moment, and worrying that I haven't typed anything for a few minutes.  The phosphors are probably burning out as we speak.

My biggest worry, though, is the hard drive.  I just don't trust mechanical things.  Surely it can't go on spinning and spinning without some accumulation of wear and tear.  The question is which is worse -- the accumulation of bearing wear from being always on, or the abrupt and traumatic transient of being powered up after shutdown?  I have the feeling that this is only a philosophical question, since my drive will be filled and obsolete in a year anyway.  Nevertheless, the worthlessness of my hard drive is a hard mindset for me to adopt, and I'd really like to know as an intellectual matter whether it is better left on or off.

The hard drive question has echoes back to that childhood argument about the light bulbs.  Who has experienced a light bulb simply burning out while it has been glowing?  Everyone knows that bulbs pop at the instant of being turned on.  The thermal transient from being awakened seems to be more destructive than the normal deterioration of the tungsten when the light is illuminating.  Does this also apply to hard drives?

All of this reasoning leaves only one remaining concern -- those rainforests.  Let's say there are 100 million PCs in the United States, and they all use about 200 watts of power.  If they're all left on continuously, that is an annual energy usage of about 200 billion kilowatt-hours.  How many trees does this consume, or how much does this deplete our fossil fuel supply?  I don't know, but I worry about things like this.

Now I 'm turning off my PC.  I'm sorry, I just can't help it.


Robert W. Lucky