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Invisible wrote:
> Picture the scene:
>
> I get called to a PC that won't boot any more. I remove one of the PCI
> cards, and suddenly the PC works perfectly. Hmm.
>
> On closer inspection, one of the ICs on the PCI card looks... Well let's
> put it this way. The writing appears to be scortched. The surface of the
> IC is apparently damp with an oily liquid. There's a bulge in the
> surface of the IC, together with a few small cracks.
>
> Here's a question for you: Why would an IC suddenly do this?
>
Someone let the magic blue smoke out.
Seriously - Any number of things can cause a cascading effect. The card
has the +12v and +5v rails. If the chip or voltage regulator has
something go wrong, it can cause *unlimited* current & poof.
As to what initiated the event, that's any number of things.
The voltage regulator on the card on in the PS could have had a problem.
The chip could have had a design defect.
The chip could have just normally failed.
A voltage spike could have fried something.
A problem that happened long ago set up the failure, but it didn't
happen until now.
etc....
Tom
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"Jim Henderson" <nos### [at] nospam com> wrote in message
news:4831ab8e$1@news.povray.org...
> Or it could've been struck by lightning (had a computer once
> that had that happen - the diagnosis was a list of components with
> "fried" written next to each component).
My parent's place got hit by lightning once many years back (back when
10-Base-2 was commonly used for networks)
Lightning directly hit the phone line that was connected to a modem. Modem
connected to PC, PC onto network cable that had 4 other machines attached.
We never found the modem, just some fragments strewn across the office.
Total casualties - 3 complete PCs, 1 network cable, 2 network cards, 1
modem.
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On Mon, 19 May 2008 21:58:09 +0200, Gail Shaw wrote:
> My parent's place got hit by lightning once many years back (back when
> 10-Base-2 was commonly used for networks) Lightning directly hit the
> phone line that was connected to a modem. Modem connected to PC, PC onto
> network cable that had 4 other machines attached.
Wow.
When I was in school in Florida, I had a Vendex V20-based PC (8088
compatible) that was thinking about its first move in a game of chess
(how many remember Sargon IV?); it'd been thinking for about 20 hours
(I'd set it to the hardest level). Thunderstorm rolled in, and a
lightning strike hit the power pole outside the window (took out the
transformer). I'm sure my PC wasn't the only casualty, but all the
pieces were still in the case when that was done...
Jim
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Jim Henderson wrote:
> On Mon, 19 May 2008 21:58:09 +0200, Gail Shaw wrote:
>
>> My parent's place got hit by lightning once many years back (back when
>> 10-Base-2 was commonly used for networks) Lightning directly hit the
>> phone line that was connected to a modem. Modem connected to PC, PC onto
>> network cable that had 4 other machines attached.
>
> Wow.
>
> When I was in school in Florida, I had a Vendex V20-based PC (8088
> compatible) that was thinking about its first move in a game of chess
> (how many remember Sargon IV?); it'd been thinking for about 20 hours
> (I'd set it to the hardest level). Thunderstorm rolled in, and a
> lightning strike hit the power pole outside the window (took out the
> transformer). I'm sure my PC wasn't the only casualty, but all the
> pieces were still in the case when that was done...
>
> Jim
I guess these are the reasons I unplug my computer from both wall and
phone line during a thunderstorm...
Sam
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On Mon, 19 May 2008 14:03:46 -0700, stbenge wrote:
> Jim Henderson wrote:
>> On Mon, 19 May 2008 21:58:09 +0200, Gail Shaw wrote:
>>
>>> My parent's place got hit by lightning once many years back (back when
>>> 10-Base-2 was commonly used for networks) Lightning directly hit the
>>> phone line that was connected to a modem. Modem connected to PC, PC
>>> onto network cable that had 4 other machines attached.
>>
>> Wow.
>>
>> When I was in school in Florida, I had a Vendex V20-based PC (8088
>> compatible) that was thinking about its first move in a game of chess
>> (how many remember Sargon IV?); it'd been thinking for about 20 hours
>> (I'd set it to the hardest level). Thunderstorm rolled in, and a
>> lightning strike hit the power pole outside the window (took out the
>> transformer). I'm sure my PC wasn't the only casualty, but all the
>> pieces were still in the case when that was done...
>>
>> Jim
>
> I guess these are the reasons I unplug my computer from both wall and
> phone line during a thunderstorm...
I haven't needed to since, though. Of course I've got two decent APC
UPSes here with insurance for the equipment. Doesn't replace the data,
but also living in the desert, we don't get many thunderstorms through
here. ;-)
Jim
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> [And more importantly, how in the name of God does a device which only has
> access to a few milliwatts manage to get warm enough to physically melt??]
Chips normally draw milliwatts, they have access to much more.
The power supply is something like 500+ watts transient until a
fuse pops or something. A soldering iron draws around 20 watts...
so if you are drawing 200 watts (normal operation) it's equivalent
to running 10 soldering irons.
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"stbenge" <stb### [at] hotmailcom> wrote in message
news:4831eb31@news.povray.org...
> I guess these are the reasons I unplug my computer from both wall and
> phone line during a thunderstorm...
>
> Sam
I started doing this after loosing a Kenwood AV controller and it was on a
GOOD surge protector.
Haven't lost any computers but the moment of first flicker everything gets
unplugged from the wall.
I guess that just proves that it's not nice to fool with mother nature!
Jim
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"stbenge" <stb### [at] hotmailcom> wrote in message
news:4831eb31@news.povray.org...
>
> I guess these are the reasons I unplug my computer from both wall and
> phone line during a thunderstorm...
My parent's house is at the top of a hill in a very open area. Until
recently their house was the highest thing for a couple km in any direction.
Add that to the frequency and intensity of thunderstorms in this part of the
world in summer and you see why they tended to get hit often.
They were very grateful when the neighbour put up a thatched roof and
installed a lightnng rod.
I live is a different area and I have 4 churches very near, all with
lighning rods. I seldom bother to unplug anything in a storm. So far, no
casualties from lighning
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> one of the PCI cards
...
> [And more importantly, how in the name of God does a device which only has
> access to a few milliwatts manage to get warm enough to physically melt??]
Where in the name of God did you get the idea that a PCI card only has
access to a few milliwatts? A quick Google told me the specification says
it can draw up to 25 W, so I imagine it can draw probably up to 30 W or more
on most motherboards.
30 W is easily enough to fry a chip.
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scott wrote:
> Where in the name of God did you get the idea that a PCI card only has
> access to a few milliwatts?
PCI devices are all extremely low power? Why would they design an
interface that can supply massively more power than necessary?
> A quick Google told me the specification
> says it can draw up to 25 W, so I imagine it can draw probably up to 30
> W or more on most motherboards.
>
> 30 W is easily enough to fry a chip.
Interesting - in my experiments, devices that are supposed to heat
things tend to be rated into kW...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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