«

>
>Many people consign the PC to the "study".....an often small room, typically
>not heated if no one is in it....and the temperatures can vary hugely
>through out the year.
>
I never considered this . You will get big temp drops at night , especially in winter.

Computors used to have there own climate controlled air conditioned
rooms. Perhaps this is where we can trace this myth about leaving PC's on back to.

How many PC failures have ACTUALLY be caused by components being heated/cooled
or turned off/turned on.Perhaps some dry joints in monitors?? but who ever leaves monitors on??

On Mon, 24 Nov 2003 17:35:44 +1300, "Gordon" <>
wrote:

>On Sun, 23 Nov 2003 23:25:15 +0000, Craig Shore wrote:
>
>> On Mon, 24 Nov 2003 10:37:22 +1300, Bruce Simpson
>> <> wrote:
>>
>>>With the price of electricity now hitting over 13-cents a unit in some
>>>parts of the country and the average PC chewing about 100W even when
>>>the monitor is turned off, a machine left on permanently will consume
>>>its own value in power in 10,000 hours of operation. Surprisingly
>>>htat's less than 18 months of full-time running -- that's less than
>>>the warranty period of most machines!
>>
>> I think you're out on the maths a bit there. You've considered it at
>> 1000w haven't you?
>>
>> at 13c/kwh, 100w/hr = .013c/hr
>
>Lets try 13c/Kwh, at 100W we hace 0.013$/hr

Yeah dollars/hr, that's what I meant

>> 10,000 hours x .013 = $130
>
>Okay here
>
>>
>> 10,000 hours is 1 year and 52 days
>
>Leap years?

1 year and 51 days. Actually it was 51.something days for normal
years.

steve wrote:
> Gib Bogle allegedly said:
>
>> For years I've been leaving my computers on all the time. A
>> throwaway comment about the power used by a P4 has prompted me to
>> revisit this policy. My reasoning always was that the startup and
>> shutdown cycle is what has most effect on the lifetime of many
>> components. I wonder if there is any definitive information on
>> this. The main issue, of course, is the survival of my disk drives.
>>
>> Gib
>
> I've been told it is the changes in temperature that can wreck the
> PC. If you turn it off and on and it is in a rom that is more of less
> stable in temperature throughout the year, that's probably Ok.
>
> Many people consign the PC to the "study".....an often small room,
> typically not heated if no one is in it....and the temperatures can
> vary hugely through out the year.
>
> The resulting expansion and contraction can - over time - create
> micro-stresses in the traces that electricity flows through.
>

Extreme freezing is bad for electromechanical components that depend on
lubricants, and cycling of temperatures and humidity that causes
condensation to form is naturally not recommended. Its a big issue for VCRs,
so it probably would be for HDs too.
I have never heard of home PC failures due to "micro stresses in traces", do
you have some more info ?

On 24 Nov 2003, Craig Shore wrote

>>> 10,000 hours is 1 year and 52 days
>>
>>Leap years?
>
> 1 year and 51 days. Actually it was 51.something days for normal
> years.
>
>

1 year 51 days and 16 hours, give or take the odd millionth of a second.
(assuming a year to be a calendar year of 365.0 days).


--
Nicolaas.

- "Bother!", said Pooh as he stuffed Piglet's corpse into a trash bag

harry allegedly said:

> I have never heard of home PC failures due to "micro stresses in traces",
> do you have some more info ?

I definitely have.

You can tell if you come across a pC that willwork OK on a warm day....but
won't even start on a cold day.

With some others......it won't start on the first several attempts - maybe
freezing soon after starting to boot.....but once it is warmed up, it will
work fine....until you turn it off and it gets cold.

I've seen several systems like this over the years. Usually older ones, as
you would expect.

The symptoms will vary quite a bit - depending on what the function of the
trace is and when it is used. It might be on a video card and not on the
mobo at all.

--
Best Regards,
Steve Withers
defenestrate: The act of throwing Windows out the window and replacing it on
your PC with some other operating system.

Those electronics failed because they were defective when
manufactured. To find those defects, we thermal cycle on the
order of 100 degrees just to find those defects before high
rel equipment is shipped. We thermal cycle everything just to
find those defects. Those failures in PC traces were created
in manufacturing - not in normal operation. A new computer is
best first used at all temperature extremes - so that those
manufacturing defects are detected when the computer is still
under warranty.

If those "micro stresses" caused a failure, they had already
existed in the manufacturing process. And those "micro
stresses" were going to appear as defects anyway. But then
steve does not post what is necessary for valid science
reasoning. He posts personal speculation - that those micro
stresses were from thermal cycling only because he feels they
must have been. He does not even know why those "micro
stresses" were created.

Reality, a power cycled computer does not change temperature
enough to see any significant thermal stress. steve simply
posts symptoms as if they were proof - a violation even of
principles taught in secondary school science. He has no idea
what created those "micro stresses" and simply assumes they
must be from thermal cycling. And he never posts numbers.


steve wrote:
> harry allegedly said:

>> I have never heard of home PC failures due to "micro stresses
>> in traces", do you have some more info ?
>
> I definitely have.
>
> You can tell if you come across a pC that willwork OK on a warm
> day....but won't even start on a cold day.
>
> With some others......it won't start on the first several attempts -
> maybe freezing soon after starting to boot.....but once it is
> warmed up, it will work fine....until you turn it off and it gets
> cold.
>
> I've seen several systems like this over the years. Usually older
> ones, as you would expect.
>
> The symptoms will vary quite a bit - depending on what the function
> of the trace is and when it is used. It might be on a video card
> and not on the mobo at all.

Power cycling does affect life expectancy. For example,
one component with a lowest number was an IBM disk drive -
40,000 power cycles. That means power cycling seven times
every day for ... 15 years. Yes, power cycling does affect
life expectancy ... until we apply the perspective called
numbers.

Not one poster who recommends leaving it on will post
numbers from manufacturer data sheets or other reliable
source. Instead they wildly speculate (personal feelings not
even tempered by experience) that thermal cycling is
destructive. But again, a lie is exposed by applying
numbers. Semiconductors are manufactured by thermal cycling
over hundreds of degrees. 500+ degrees and no thermal
stress. Are the trivial tens of degrees in power cycling
going to affect anything? Of course not. More numbers they
fear to first learn.

Those who say leaving it on extends life expectancy are
simply promoting junk science. Junk scientists are obvious.
They must avoid the perspective of numbers. Numbers provided
above demonstrate perspective - that power cycling is
irrelevant. Run the computer as you would a TV.

Then it gets more interesting. Normal computer operation
involves massive power cycling. For example, that Intel CPU
requires a motherboard power supply that can go from 1 amp to
tens of amps ... not in millisecond ... but in microseconds!
That is the most severe power cycle ... that is also called
normal operation. IOW leaving a computer running is constant
power cycling. That is what digital logic does - power
cycle. Those power cycles called normal operation cause
uneven and constantly changing heating everywhere on the
computer die.

Turn it off or put it to sleep to obtain best life
expectancy. Power up does not create massive surge that myth
purveyors claim. And those myth purveyors don't even know
about the inrush current limiter - that was standard on
electronics even in 1950 TVs. Just another reason why no
massive power surge when electronics is powered on.

Leaving it on to preserve life expectancy is based upon no
manufacturer data sheets, no understanding of what is
considered hot to electronic components, and not even
knowledge of inrush current limiters. They don't bother to
first learn how thing work before making wild and speculative
declarations. It is called junk science reasoning. IOW they
must avoid numbers to promote their 'feelings' - facts be
damned.

Turn it off to preserve its life. Ignore junk scientist who
have no numbers.

Steve Robertson wrote:
> At last some facts rather than old wives tales

harry wrote:
> I have never heard of home PC failures due to "micro stresses in traces", do
> you have some more info ?

Even if it was the cause, would the price of a new part warrant an
investigation? I doubt it... easier to just replace the part.

T.N.O. wrote:
> harry wrote:
>> I have never heard of home PC failures due to "micro stresses in
>> traces", do you have some more info ?
>
> Even if it was the cause, would the price of a new part warrant an
> investigation? I doubt it... easier to just replace the part.

Not really
From the point of view of a manufacturer, susceptability to such a fault
would result in an unsustainable number of warranty claims from resellers.

steve wrote:
> harry allegedly said:
>
>> I have never heard of home PC failures due to "micro stresses in
>> traces", do you have some more info ?
>
> I definitely have.
>
> You can tell if you come across a pC that willwork OK on a warm
> day....but won't even start on a cold day.
>
> With some others......it won't start on the first several attempts -
> maybe freezing soon after starting to boot.....but once it is warmed
> up, it will work fine....until you turn it off and it gets cold.
>
> I've seen several systems like this over the years. Usually older
> ones, as you would expect.
>
> The symptoms will vary quite a bit - depending on what the function
> of the trace is and when it is used. It might be on a video card and
> not on the mobo at all.

Stress won't cause a conductor path to cease to pass current, when the
stress causes breakage the damage would be permanent.
I'm willing to stick my video card in the freezer and then de-frost it.
It is highly improbable that the coefficient of expansion of circuit board
copper, or its ductility would cause fracturing between operating
temperature and low temperate climate temperatures.
Startup problems in cold weather are more likely to be bearings sticking on
CPU coolers with sensing, or on HDs, or condensation on cold metal parts
causing switching power supplies to fail to start.