dixon@pdn.paradyne.com (Tom Dixon) (09/18/90)
With todays pc hardware, exactly how dangerous is each power cycle? If you power your office unit off every night, are you in for early hardware failures? Or is this all propaganda spread by electric power companies? I propose this assuming an ibm pc clone, with hard drive, utilized five days a week. Currently, some people around our plant are recommending that we shut all the equipment off to save on the power bill, and I'm afraid that this is not the best idea. I seem to remember that a few years ago, the recommendation was that if a pc was going to be on five days a week, you were wise to leave it on all of the time. The power used was insignificant next to repair costs from drive failures and hardware problems related to frequent power cycling. The act of powering up in those units was apparently very hard on the hardware. But today we have newer (and better?) units. So with current technology, what's the story? -- Thomas M. Dixon Jr. dixon@pdn.paradyne.com Software Engineer uunet!pdn!dixon AT&T Paradyne, Largo, Fl
chooft@ruunsa.fys.ruu.nl (Rob Hooft) (09/18/90)
In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com (Tom Dixon) writes: >With todays pc hardware, exactly how dangerous is each power cycle? >If you power your office unit off every night, are you in for early >hardware failures? Or is this all propaganda spread by electric power >companies? I run an XT since 17 feb 87, and upgraded with harddisk at 27 feb 87. This machine is powered up and down at least once a day, usually more, at least six days a week. I never had a problem. -- Rob Hooft, Chemistry department University of Utrecht. hooft@hutruu54.bitnet hooft@chem.ruu.nl chooft@fys.ruu.nl
jc58+@andrew.cmu.edu (Johnny J. Chin) (09/18/90)
Power On and Off a PC puts the most wear on your hard drives. The spin down
and spin up of the platters causes the spindle to wear out. Leaving the
system on all the time allows the spindle to spin with less friction, thus
less wear.
As for the components of the computer (ie. the silicon chips), the power spikes
induced by a power on decrease its life (this is more so with the denser VLSI
chips because of the narrower width of the electrical lines).
The problem with leaving PCs on is the load that is induced on the transformers
out in the street. PCs use a switching power supply; what this means is that
the power supply switches "on and off" 60 cycles per second. This does NOT
mean that the PC turns on and off 60 times every second. Because of this
"on and off" of the switching power supply, a larger load is demanded from
the transformers (due to lots of small sudden demands for power).
Ultimately, what should you do? Leave it on or turn if off daily?
Well, my suggestion is ... if you use the computer a lot (ie. more than 10
hours a day) and use the hard drive a lot during this time (ie. not sitting
in your word processor all day, but doing reads/writes), I would leave it on.
Otherwise, I'd turn them off at night. I use my PC about 8-10 hours a day
with about a lot of reading/writing; I still turn off my PC when I don't plan
on using it for several hours. Besides, it saves on the electric bill and
lowers the chances of getting spikes and brown-outs.
Remember, this is my opinion only.
__________ ___
/ \ / / /_/ / /\/
_/ / / / __/. /__ / / / / /
/ / /
/ / Happy Computing ... ARPAnet: Johnny.J.Chin@andrew.cmu.edu
/ ------- / BITnet: jc58@andrew
\__________/ UUCP: ...!harvard!andrew.cmu.edu!jc58
Computer Dr.
Disclaimer: The views expressed herein are STRICTLY my own, and not CMU's.art@wciu.EDU (Art Nicolaysen) (09/19/90)
>In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com >(Tom Dixon) writes: > >With todays pc hardware, exactly how dangerous is each power cycle? >If you power your office unit off every night, are you in for early >hardware failures? Or is this all propaganda spread by electric power >companies? > Having worked in a large multiuser environment, my prejudice is to leave a computer powered up unless setup, repairs, etc. dictate otherwise. I have never observed 24-hour operation as a sole cause of downtime for computers or peripherals. I leave my machine on all the time because: 1) The hassle factor is less for paying power bills* than for getting dead equipment repaired or replaced. 2) Equipment will become obsolete before rotating parts (e.g., disk drive bearings) fail. 3) A constant application of power doesn't stress non-moving (ICs, resistors, etc) components as much as power cycling does (consider the thermal stresses caused by heating/cooling). 4) Subjective experience. In my last job, over a 2.5 year period, I replaced 1 terminal in office A vs 4 terminals in office B. The difference? The users in Office A left their terminals on all the time (after an explanation of the above points). The other users insisted on powering down every night. 5) Varied inflammatory arguments that have resulted in shouting matches and are best confined to alt.religion.computers. In any case, I am a strong advocate of powering down the monitor if no screensaver utility is available. Images burned into the screen are inimical to getting work done. BTW, I see this as more of an emotional than a factual decision. In our office, we have a mixture of XTs, ATs and 386s. Half the users leave their machines on all the time, and the rest turn them off at the end of the day. * The utility bills vs. repair bills analysis is left as an exercise for the reader. Failure rate analysis... I don't have the statistics to attempt it. Anybody got some? -- Art Nicolaysen William Carey Int'l University (Global Mapping) art@wciu.edu Pasadena CA 91104
ssingh@watserv1.waterloo.edu ($anjay [+] $ingh - Indy Studz) (09/19/90)
In article <1480@ruunsa.fys.ruu.nl> chooft@ruunsa.fys.ruu.nl (Rob Hooft) writes: >In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com >(Tom Dixon) writes: > >>With todays pc hardware, exactly how dangerous is each power cycle? >>If you power your office unit off every night, are you in for early >>hardware failures? Or is this all propaganda spread by electric power >>companies? > >I run an XT since 17 feb 87, and upgraded with harddisk at 27 feb 87. This >machine is powered up and down at least once a day, usually more, at least >six days a week. I never had a problem. > >-- >Rob Hooft, Chemistry department University of Utrecht. >hooft@hutruu54.bitnet hooft@chem.ruu.nl chooft@fys.ruu.nl We had a discussion on this topic some months ago on the net. The general concensus was that with the newer, better designed power supplies, it is okay to turn the machine off and on more often than once a day. Some years ago, it would have been smarter to leave your computer on all the time because the power supplies would allow such large surges through the machine on power-up. Unless the power supply is faulty to begin with, five years down the line, you will have moved up to a new computer with a new power supply to begin again with. -- "No one had the guts... until now..." |-"psychotic" $anjay [+] $ingh ssingh@watserv1.[u]waterloo.{edu|cdn}/[ca] -| watserv1%rn alt.[CENSORED BY JOHNNY WONG, THE MAN WHO PROTECTS ME FROM MYSELF] !two-live-crew!cindy's_torment!bambina_child!ALT.[group]!Public_Enemy!N.W.A.!
kabra437@pallas.athenanet.com (Ken Abrams) (09/20/90)
In article <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com (Tom Dixon) writes: > >With todays pc hardware, exactly how dangerous is each power cycle? Tell me, o' swami, how likely is it that I will be struck by lightening...... I doubt that anyone can tell you EXACTLY how dangerous the power cycle is. >If you power your office unit off every night, are you in for early >hardware failures? Or is this all propaganda spread by electric power >companies? >I seem to remember that a few years ago, the recommendation was that if >a pc was going to be on five days a week, you were wise to leave it on >all of the time. >But today we have newer (and better?) units. So with current >technology, what's the story? From the tone of your article, I think you have a pretty good idea already that things have changed some since the original recommendation was formulated. It has survived, in part, from the time when things like tubes took a thermal shock going from room temp. to several hundred degrees in a few seconds. That situation doesn't really apply anymore (at least not to the same degree). This has been kind of a pet peeve with me for several years and I have a lot of very specific opinions on the subject. Most of those opinions have been summed up quite nicely by people who are highly respected in the trade journals lately. I have seen two articles where both authors concluded that "on at 8, off at 5" is a good compromise in most average situations. I wish I could name the mags and authors but I read so MANY things........ If you really want to hear a more detailed opinion, drop me a mail message. -- ======================================================== Ken Abrams uunet!pallas!kabra437 Illinois Bell kabra437@athenanet.com Springfield (voice) 217-753-7965
poffen@sj.ate.slb.com (Russell Poffenberger) (09/22/90)
In article <1990Sep19.144759.7880@watserv1.waterloo.edu> ssingh@watserv1.waterloo.edu ($anjay [+] $ingh - Indy Studz) writes: >In article <1480@ruunsa.fys.ruu.nl> chooft@ruunsa.fys.ruu.nl (Rob Hooft) writes: >>In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com >>(Tom Dixon) writes: >> >>>With todays pc hardware, exactly how dangerous is each power cycle? >>>If you power your office unit off every night, are you in for early >>>hardware failures? Or is this all propaganda spread by electric power >>>companies? >> >>I run an XT since 17 feb 87, and upgraded with harddisk at 27 feb 87. This >>machine is powered up and down at least once a day, usually more, at least >>six days a week. I never had a problem. >> >>-- >>Rob Hooft, Chemistry department University of Utrecht. >>hooft@hutruu54.bitnet hooft@chem.ruu.nl chooft@fys.ruu.nl > >We had a discussion on this topic some months ago on the net. The general >concensus was that with the newer, better designed power supplies, it >is okay to turn the machine off and on more often than once a day. > >Some years ago, it would have been smarter to leave your computer on >all the time because the power supplies would allow such large surges >through the machine on power-up. > >Unless the power supply is faulty to begin with, five years down the line, >you will have moved up to a new computer with a new power supply to begin >again with. > > It isn't so much the power surges that can cause damage, but internal parts, (especially CPU's) generate heat and run up to 50 degrees C (at junction) hotter than room temperature. When you turn the system off, it cools down. Turn it on, it heats up. This thermal cycling definitely DOES have a detrimental effect on the part, mainly the package stresses and the lead bonding to the die inside. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254
ted@helios.ucsc.edu (Ted Cantrall) (09/26/90)
>>In <1990Sep17.205845.12803@pdn.paradyne.com> dixon@pdn.paradyne.com >>(Tom Dixon) writes: >>With todays pc hardware, exactly how dangerous is each power cycle? >>If you power your office unit off every night, are you in for early >>hardware failures? Or is this all propaganda spread by electric power On page 32 on the Sept 24 INFOWORLD, Steve Gibson (of Gibson Research and SpinRite fame) discusses several aspects of this long running debate. He says "I have determined that hard disk-based personal computer workstations should never be turned off." Near the end of the article he modifies that stance somewhat, but in the bulk of the article he talks of hard disk heads jerking on power-up, surge currents in motors, CRT filiments and other parts. Thermal cycling may have been more obvious in the days of vacuum tubes, but have you ever put your finger on some of the large chips in your PC? You can cook eggs on some of them! He also quotes hard disk manufacturers say that thermal cycling is harder on bearings that continous operation. -ted- ------------------------------------------------------------------------------- ted@helios.ucsc.edu |"He has showed you, O man, what is good; and what does the W (408)459-2110 |Lord require of you but to do justice and to love kindness H (408)423-2444 |and to walk humbly with your God?" Micah 6:8 (RSV)
kabra437@pallas.athenanet.com (Ken Abrams) (09/26/90)
In an earlier post, I offered to elaborate on my opinions and at least one user took me up on the offer and suggested I post instead of mail so this is for Michiel de Vries, et al: The best discussion I have seen recently on the subject is in PC MAGAZINE, Vol. 9, Num. 15, Sept. 11, 1990 in the ADVISOR section on page 27. Although I am not (necessarily) endorsing this publication or the author, in this case I am in general agreement with this article. I subscribe to the "on at 8, off at 5" theory of operation. I believe that in most "average" situations, the dangers of leaving things powered on overnight and weekends outweighs the perceived benefit of avoiding the once a day thermal cycle. A constantly running machine draws in a LOT of dust and dirt. It is vulnerable to power line fluctuations and being bumped by the janitor. It is more vulnerable to prying eyes and fingers. It also wastes a LOT of power. There is a small but real posibility that something will short out and start a fire. Regardless of what you do to the CPU, I think there is common agreement that CRTs should be shut off when not in use for prolonged periods. A screen blanker is better than nothing but the guns in a CRT somethimes wear out from extended use too. -- ======================================================== Ken Abrams uunet!pallas!kabra437 Illinois Bell kabra437@athenanet.com Springfield (voice) 217-753-7965
robertb@cs.washington.edu (Robert Bedichek) (09/26/90)
In article <8axQEga00VY642bGAb@andrew.cmu.edu> jc58+@andrew.cmu.edu (Johnny J. Chin) writes: >Power On and Off a PC puts the most wear on your hard drives. The spin down >and spin up of the platters causes the spindle to wear out. Leaving the >system on all the time allows the spindle to spin with less friction, thus >less wear. I've seen this claim before, but never the hard data to back it up. At least you have to have some rough equivalence between power cycles and hours of continuous operation. What you and others suggest, without meaning to, I imagine, is that it is better to leave a PC on for a year than to turn it on for a minute, then off, and leave it for the rest of the year. It seems unlikely that this is true. If it isn't, make it ten years, or a hundred that the computer is left off after the single power cycle. >As for the components of the computer (ie. the silicon chips), the power spikes >induced by a power on decrease its life (this is more so with the denser VLSI >chips because of the narrower width of the electrical lines). What power spikes "induced by a power on"? I've been looking at power supply outputs with scopes on and off for twenty years and I've never seen under or over shoot at power on or off in a commercial supply or one that I designed. I'm not saying that it never happens, but you talk as if it is a fact of life. And what this has to do with narrower metal lines I can not imagine. Do the few milliseconds during which a power supply rail come up contribute to electromigration? This seems far fetched to me. Do you think it blows holes in the narrower silicon oxide gates? I really doubt that. >The problem with leaving PCs on is the load that is induced on the transformers >out in the street. PCs use a switching power supply; what this means is that >the power supply switches "on and off" 60 cycles per second. This does NOT >mean that the PC turns on and off 60 times every second. Because of this >"on and off" of the switching power supply, a larger load is demanded from >the transformers (due to lots of small sudden demands for power). This makes no sense to me at all. What is the problem w/ a switching supply and power transformers that supply them? Switching supplies typically switch at 20 to 30 KHz, not 60 Hz. Who is this a problem for? The power company? The computer user? > >Ultimately, what should you do? Leave it on or turn if off daily? >Well, my suggestion is ... if you use the computer a lot (ie. more than 10 >hours a day) and use the hard drive a lot during this time (ie. not sitting >in your word processor all day, but doing reads/writes), I would leave it on. Intuition, often a fine thing, but what is this intuition based on? >Otherwise, I'd turn them off at night. I use my PC about 8-10 hours a day >with about a lot of reading/writing; I still turn off my PC when I don't plan >on using it for several hours. Besides, it saves on the electric bill and >lowers the chances of getting spikes and brown-outs. > >Remember, this is my opinion only. But so much is stated as if it were fact. I am not saying that leaving your computer on all the time is a bad idea. I am taking issue with the assertions made Mr. Chin in support of his suggestion. Robert Bedichek robertb@cs.washington.edu
poffen@sj.ate.slb.com (Russell Poffenberger) (09/28/90)
In article <8axQEga00VY642bGAb@andrew.cmu.edu> jc58+@andrew.cmu.edu (Johnny J. Chin) writes: >Power On and Off a PC puts the most wear on your hard drives. The spin down >and spin up of the platters causes the spindle to wear out. Leaving the >system on all the time allows the spindle to spin with less friction, thus >less wear. > >As for the components of the computer (ie. the silicon chips), the power spikes >induced by a power on decrease its life (this is more so with the denser VLSI >chips because of the narrower width of the electrical lines). > The problem is more due to thermal expansion/contraction as the chips heat up and cool of with power on/off. A good power supply "glitches" very little. >The problem with leaving PCs on is the load that is induced on the transformers >out in the street. PCs use a switching power supply; what this means is that >the power supply switches "on and off" 60 cycles per second. This does NOT >mean that the PC turns on and off 60 times every second. Because of this >"on and off" of the switching power supply, a larger load is demanded from >the transformers (due to lots of small sudden demands for power). This is simply not correct. First of all, the "switching" section of the supply is powered by DC, after the AC line as been rectified and filtered. The filtering (using large capacitors) masks any load changes caused by the switching action of the supply. Second, switching supplies switch MUCH faster than 60Hz, more along the line of 50Khz and up. Generally, the higher the frequency, the smaller the power supply (to a point) because the inductors used are smaller. Russ Poffenberger DOMAIN: poffen@sj.ate.slb.com Schlumberger Technologies UUCP: {uunet,decwrl,amdahl}!sjsca4!poffen 1601 Technology Drive CIS: 72401,276 San Jose, Ca. 95110 (408)437-5254
grege@gold.GVG.TEK.COM (Gregory Ebert) (09/28/90)
poffen@sj.ate.slb.com (Russell Poffenberger) writes: > >This is simply not correct. First of all, the "switching" section of the supply >is powered by DC, after the AC line as been rectified and filtered. The >filtering (using large capacitors) masks any load changes caused by the >switching action of the supply. There IS a problem, though, with the rectifier section: It makes NASTY current spikes when the capacitor charges (briefly). There was a large fire in downtown LA which was attributed to the switchmode power supplies in PC's (Union Bank building, not ARCO tower). The power distribution system assumed balanced 3-phase loads, but many of the PC's, which have a non-unity power factor, caused a large imbalance in the power system. This results in a large current in the neutral line, which would normally be zero, and an electrical fire started. The degree of imbalance peaked at night because PC's were left on, while lights and air-conditioning equipment were cut back. ------------------------------------------------------------------------- ##### {uunet!tektronix!gold!grege} Register to vote, then ## | ## grege@gold.gvg.tek.com vote responsibly # | # # /|\ # Support the First Amendment, not the party that attacks it #/ | \# "I was, BANNED in the USA" - 2 Live Crew #######
richard@pegasus.com (Richard Foulk) (10/03/90)
>>>With todays pc hardware, exactly how dangerous is each power cycle? >>>If you power your office unit off every night, are you in for early >>>hardware failures? Or is this all propaganda spread by electric power >On page 32 on the Sept 24 INFOWORLD, Steve Gibson (of Gibson Research and >SpinRite fame) discusses several aspects of this long running debate. >He says "I have determined that hard disk-based personal computer >workstations should never be turned off." [...] Considering some of the lame and stupid things Spinrite does I wouldn't put too much stalk in Gibson's word on the subject. If you use Spinrite with the defaults it will try to bring factory-bad-blocks back into use. If you do something that stupid you'd have good reason to keep things powered up for maximum temperature stability, etc. I prefer leaving things powered up myself, but here it's also for some protection against humidity. -- Richard Foulk richard@pegasus.com