Home PCs, year 2006 - turn off at night or leave on?

About 5 years ago, I asked all my PC Tech friends this question -- for home users, should they turn their PCs (old and new) off at night, or leave them on.

Exactly half the guys said -- Turn it off. You'll get less dust -- dust is the killer.  General rule of thumb -- less time on means less heat, means longer life.

The other half of the guys said -- Leave it on.  Parts burn out when you turn on the PC and the current runs thru the PC. So just leave it on, using restart when necessary. If it's a good PC, the fan will keep it cool. And a screen will keep the dust out, etc etc.

Do you guys agree, is it 50/50? Or has it changed in the last 5 years?
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Gary CaseRetiredCommented:
You'll probably get the same 50/50 split, but I'll offer my opinion anyway:   If you use the PC every day for any reasonable length of time, AND have it on a UPS (which, in my opinion, is a mandatory "option" for every PC), then leave it on.   The stress of the turn on/turn off cycle outweights any heat-reduction benefit for a well-ventilated modern PC.   But ONLY if there's no chance of it suffering through an unplanned power outage -- which is one of the worst events in the "life" of a modern PC.   With a UPS, the latter possibility is eliminated, so just leave it on.

None of the PC's I use (4 of the 10 or so I have) are ever turned off -- the one I'm typing this on hasn't been turned off (except for routine "blow-out-the-dust" maintenance) since I built it nearly two years ago.

If your PC is NOT on a UPS -- or if you don't use it regularly -- then turn it off.
Ditto what garycase said. It depends on how the system is used.
Mine only runs 3-4 hours a day, so I turn them off. And I have them on an UPS. Those 1 second power outages really irritate me.
Gary CaseRetiredCommented:
... I agree that even if you turn them off they should still be on UPS's.   ALL of my PC's are on UPS's -- and when I have a friend's here to work on, it's on a UPS too :-)   I simply do NOT expose any PC to unplanned power outages.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
ditto on the UPS.  Ultimately, though, it doesn't matter.  Do what you want.  The components in your computer are pretty much the same as a low end server and those are typically on 24x7x365.  On the other hand, power costs money.  In my neck of the woods, about $15-20 per month per PC on 24x7x365.  If your biggest problem is you hate waiting for it to boot, enable hibernation and hibernate it every time you leave or automatically after 30 to 60 minutes.  That will save your system in the exact state its in and power it off.  Then resume from where you left off when you turn it back on.
to counterbalance above comments : i always turn my PC's off.
I have learnt that the technology nowadays is far better then some years ago, and causes next to nil problems.
Generally speaking, i agree with the fact that the pwroff/on cycle can cause thermal crimping and contact problems, but it seems that the technology is able to cope with it.
Other reasons are :
-power used ( we use too much power all over the planet)
-OS housekeeping : unlike server OS'es, Xp does not have housekeeping routines, so i suggest a reboot at regular times, so it looks good practise to me to do it everyday.
-increased fire hazard
The fable I use to explain why a pc should be left on, is to think about the light bulbs in your house.

How often have you just been sitting there and have the room suddenly go dark because a bulb has blown out?

How often have you walked into a dark room and turned on the light, only to be greeted with a quick flash and then darkness?

For most people the second is the most common occurance.

I then explain that this is because the toughest time in a piece of electronic's life is the first few miliseconds when the power is first applied.

nobus has a point that hardware is built better than in the past, but the laws of physics are still the same.  The fire hazard concern is the main reason to be sure and use UL approved components.

At the very least you should reduce the number of power cycles to the minimum, such as leaving the machine run during the day, if you expect to be using it again.  Turing it off 4-5 times a day will reduce its life span...
dgrrrAuthor Commented:
Wow, great answers, on both sides..

I do NOT have a UPS. Even tho the breaker cuts off power about once a week.  

My assumptions (most of which are probably wrong)
(1) losing power temporarily in a power outage is the same (to the OS and hardware) as unplugging a live pc with no UPS
(2) the above 2 situations are identical, in terms of stressing the hardware, as shutting down the computer, waiting, and turning it back on (booting windows) -- but they are harder on the OS... (in other words, teh only benefit of using shutdown vs unplug, if for the OS, not the hardware
(3) using restart rather that shutdown avoids the "electrical stress" of turning power off then on
(4) turning off and and restarting the operating system is good for the Operating system, as nobus said.

Are any of these right?

Gary CaseRetiredCommented:
(1)  No -- an outage will generally have much more of a transient waveform and can cause much more damage; although unplugging the PC is also not good for it.

(2)  Absolutely not -- shutting down the PC causes a single, controlled loss of power to all of the components;  unplugging it can cause a momentary spike due to the loss of grounding; and an outage is often accompanied by several spikes (within a few milliseconds) that are the worst yet.

(3)  Yes -- this is a control line that resets everything programmatically and does not cause the same level of stress on components as a power off/on cycle.

(4)  Not really "good" for it; but rebooting will cause all of the drivers to be reinitialized; buffers to be reset; etc. -- and if any of these have been in any way corrupted a restart will resolve that.   With earlier OS's that had noticeable memory leaks (e.g. the 9x OS's) this was definitely a desirable thing;  with NT-based OS's (NT, 2000, XP) it's much less necessary.   I haven't rebooted my system for weeks at a time -- it generally only gets rebooted when an update requires it.
Thank you much.    : )

Garycase needs to take a vacation. I am getting tired of posting "Ditto" behind him.   : P
Gary CaseRetiredCommented:
dgrrr -- if you haven't figured it out yet, let me make it crystal clear:  the single biggest improvement you could make in the reliability of your system is to buy a good UPS ==> do not buy a low-end unit without automatic voltage regulation (AVR).

... interestingly, I was at a friend's house yesterday looking at the damage he had last week from a direct lightning strike.   Hit the roof over the garage and did quite a bit of damage to the house; blew out the A/C unit; fried several major appliances; and destroyed both of the UPS units he had purchased a few months ago on my recommendation -- but BOTH computers (which had, in fact, been on when the strike hit) are fine :-)    Needless to say, he's now a very strong believer in my "UPS is a mandatory accessory" theory.   And Belkin (the UPS's he had were these:  http://www.newegg.com/Product/Product.asp?Item=N82E16842101219) is replacing both units for free.
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