spontaneous reboot problem

C

CBFalconer

Snipped all the comments.

I am new to this forum and was enjoying the interchange of ideas
when Rod proceded to make comment and not help.

DO I need to ignore anything from this person?

Yes. He is a known troll. If you shift to a real newsreader you
can just PLONK him and his mouthings will no longer annoy you
(except when quoted by someone else).
 
K

kony

Snipped all the comments.

I am new to this forum and was enjoying the interchange of ideas when
Rod proceded to make comment and not help.

DO I need to ignore anything from this person?

It would be easier.

Now to the problem at hand....

I have worked on computers for many years.
Flaky PSU's are sometimes just that, flaky.
They do not cause a failure, or reboot until it happens.
Switching power feeds to the HD temporarily cured it.
This really indicates a PSU problem.
However, swapping out, to cure, is not very specific,as the other
helpers have noted.

Please take the time to be thorough.
YB

If the PSU problem is intermittent, you're left detecting it
exactly when it happens. Do you have the facilities to do
this? For example an o'scope or fast logging multimeter,
though of course it can't be hooked up to the PC that is
resetting itself to do logging.

You might unplug the PSU from AC for a few minutes and then
open, examine it. With luck you might find visual
indication of a failure like vented capacitors, or if you
have a multimeter you can check things like shorted/open
rectifiers or switching transistors, cold solder joints.
Otherwise such an intermittent problem still leaves you
waiting to catch it happening again, as the parts can't be
totally unworking yet to be able to turn the system back on
at all.

In other words, there are only two real alternatives, either
you have the tools, ability, and patience to take apart your
PSU and apply various load and temp conditions to it while
logging the output quality, or you don't and can only test
or look for basic things before swapping in a different PSU.
 
M

Mark N

w_tom said:
Increased memory voltage? Increases CPU voltage. That is
shotgunning. It learns nothing useful. And if it did fix anything,
it only 'cured symptoms'.

You are still not doing what is said in CSI - follow the evidence.
Trying to fix it rather than first collecting facts only leads to ...
well the previous post described this as experience without basic
knowledge. Due to such speculation, then things that look like
solutions actually solve nothing. Terms like 'spinning your wheels'
apply because advise that would 'follow the evidence' was ignored.

Everything posted implies something in a power supply 'system' has
long been defective. You have used subjective reasoning to declare
that power supply good. Power supply could have been insufficient two
years ago. With age and that optical drive, then the defective power
supply finally created failures. Remember what the meter does? It
may even find problems long before failures happen. Had you used the
meter two years ago, then maybe this problem would have never
occurred.

Worse - you are thinking binary. The world is ternary. Notice
three conditions. a) Power supply good and system works. b) Power
supply defecitve but system works. c) Power supply defective and
system fails. All three exist. Your reasoning has assumed only a)
and c). But again why shotgunning is avoided. But again why those
with only experience sometimes only cure symptoms.

You have established zero items as operational. After so much
effort, nothing is known. Nothing has been accomplished. Get the
meter. In but two minutes, those numbers would have made major
accomplishments. Start a process of learning what is and is not
sufficient. Stop doing the 'try this and try that'. You have
demonstrated only again why shotgunning is not very successful and why
shotgunning takes so much more time. After everything posted, we are
still no closer to a solution because you did not get the meter.

How do we know nothing is being learned. You are trying to fix it.
That comes later. First get the facts. Did you also collect data
from the system (event) log? Another useful fact that long ago might
have identified the problem. Just another example of why we first
collect data long before trying to fix anything.

It is not odd "that this problem didn't crop up for several weeks".
That common occurance is also why shotgunning is so unreliable. But
again, you made an assumption, then drew conclusions from that
assumption. That is also how wild speculation only complicates a
problem. Follow the evidence. Establish what is good. Get the meter
so that every effort results in something other than wild speculation.

So now you will suspect the video card? On what data? Again, more
shotgunning. If another video card changes things, does that mean the
video card is defective? No. It also means the power supply 'system'
is defective, heat is a problem, motherboard bus is defective,
software magically went defective, and ... Stop shotgunning. Or
just telll everyone to go away because you really don't want help.
You have ZERO reasons to blame the video card. ZERO. But you are
shotgunning.

My, but you seem to enjoy being superior. Understand that I appreciate
the help, though. To this point I've not done all that much, just tried
to observe what has been happening and considering suggestions. What I
can easily do that might eliminate at least some long odds possibilities
I have done like (yes) swapping out the video card and running the pair
of memory modules by themselves, and it seems those possibilities can
now be eliminated. I have no idea how good the power supply is, and have
no particular reason to believe it's good. I do have an old power supply
that I've considered trying, but not sure that the connectors are the
necessary ones. Just haven't gotten to it yet. Regarding the voltage
meter, I have no idea how to use one, but it seems a good idea.
Understand that I know very little about electronics, and I'm hardly a
PC expert. I built the PC originally to obtain a better understanding of
the things, have upgraded it significantly, and have followed my nose
successfully through all the problems I've had so far, which fortunately
have mostly been on the software side, and have learned a lot in the
process. But, again, I ain't no expert.

The power supply seems like an increasingly good candidate to me. The
heat readings, accurate in absolute terms or not, and the rebooting
behavior suggest that it's not a heat problem to me. I have no idea what
would be evidence of a mobo failure, beyond visibly bad capacitors, so
maybe that's left when other things have been eliminated. I can't see
any point to taking a hair dryer to the thing, given the wonky behavior
now, and I can't turn back the clock to when I first rebuilt the thing.
In the end I may have to either start swapping out parts, based on best
guesses, or bring it to someone who does understand the things and has
the parts to do more thorough testing.

So if you feel inclined to give me a few pointers on how to test the PS,
I'm all ears...
 
W

w_tom

Apparently an emotion is perceived. I make no effort to be
politically correct. Instead are posted straight, blunt, and honest
facts. Have no idea why one might confuse blunt and honest reasons
with a perceived emotion. Posted was how to solve your problem ASAP -
and reasons why.

A meter is so complex that it is sold in K-mart. I keep making that
point because so many fear to learn things new. How could you change
CPU voltages when that is clearly more complex and (for all you know)
could damage the processor (a concept called overstress)? For
example, it you found a defective video card, well, that may only be a
function of a defective supply. IOW you still have no definitive fact
because the computer's foundation is completely unknown AND suspect.
Labor resulted in no definitive results.

Anything or everything can appear intermittent if a power supply
'system' is suspect. If shotgunning, then little that is definitive
is learned. Do you plane doors inside a house when its foundation is
crumbling? Or do you fix the foundation? A defective power supply
'system' is the one item that can cause everything to appear
defective.

Why fear something new only because it is new? Others with only a
high school education use a meter - which is why a multimeter is sold
even in K-mart. An Ipod is more complex. Should we also fear Ipods?
Get the meter. Don't second guess the meter (or a hairdryer).

Shotgun with another power supply? Then previous posts were not
comprehended. Remember so many reasons why you need the meter? A
perfectly good power supply may fail in this system - no definitive
answer obtained. Making changes may make the problem exponentially
more complex. A slew of other reasons previously posted says use the
meter. Two trivial minutes provides useful information both to you
and to those offering assistance. No numbers only starves your help.

What would be evidence of a motherboard failure? You nor I care
yet. Break a problem down into parts; then diagnosing those parts -
piece by piece. Later we can explain why a hairdryer (as we do even
with aerospace hardware) is a powerful tool. You don't yet have a
clue as to why that tool is so useful; no do we yet care. Forget the
motherboard as any reason for failure. KISS. Get the meter.

You cannot eliminate a single hardware possibility until we have
established the foundation. Things you claim to have eliminated are
still suspects because what you did could not yet provide a
'definitive' answer. Only answer worth anything is a 'definitive'
answer.

Best way to test a power supply has been provided twice over.
Disconnect nothing. Swap nothing. Even leave the optical drive
connected. Get the meter. Do what was posted above or in "When your
computer dies without warning....." at:
http://tinyurl.com/yvf9vh
And then post those numbers (regardless of what you have concluded)
because those numbers may also contain other useful facts. You have no
idea yet the power of what is recommended. Learn some new tricks.
But more important, appreciate the power of 'breaking a problem down
into parts' AND how to 'follow the evidence'. Amazing how many people
do not understand that principle even when watching 'CSI' every week.
Instead they want to fix something based only on guesses. Even car
mechanics get fired for diagnosing that way.

Kony also demonstrated the same concept. Do you replace a
motherboard only because motherboard might have bad capacitors? Of
course not. First look at those capacitors - collect facts. Change
nothing until a reason exists - ie bulging caps.

Well, my car is burning oil; leaving a trail of smoke. Maybe it's
the gasoline. I will try another brand. That might fix it. Your
response to spontaneous reboots used the exact same flawed reasoning.

Get the meter. Measure those voltages without disconnecting or
removing anything.
 
A

Andrew Smallshaw

Apologies for the delay in repsonding to this but my news server
seems to be expiring articles very quickly at the moment. Methinks
we're going down a blind alley with this discussion of lighting
but what the hell...

Nothing arbitrary was posted. Experience alone (without fundamental
facts and numbers) results in junk science reasoning - also called
speculation. That guess on illumination is just that - speculation.

My 10% figure for perceived dip in illumination wasn't plucked from
thin air. As an amatuer astronomer I'm well aware of the eye's
limitations. I consulted a book on optics from the shelf - the
eye is pretty fundamental and receives much coverage. The figure
was taken from a graph. I've found something similar online at:

http://www.engineering.uiowa.edu/~aip/Lectures/eye_phys_lecture.pdf
(page 16)

A filament light bulb will typically reach 40% rated luminosity at
around 0.76x rated voltage [1]. In my 230 V example this works
out to 175 V - that's not a country mile from the 184 V my UPS
trips at, and it's above the unit's less sensitive settings.
Your AC voltages must maintain specific limits at different points
in household distribution. 230 volts must not drop below 205 volts.

True, but the 10% tolerance applies on a continuous basis only, it
does not cover transients. There's no question that the voltage
drops below this as the UPS does trip.
Meanwhile a 230 volts UPS may flip to battery backup mode typically
at 200 volts. (Yours trips at an untypically low 185 volts - well look
how much lower all computers must work so that your UPS can trip at
185).

Like most UPSs aimed at the computer market, its trip voltage is
user configurable, in this case over the range 160-196 V. The 184
(presumably nominal) is simply the stock setting.
If Andrews' UPS is tripping daily, experience and the numbers
says Andrews should identify a marginal wiring problem - maybe a loose
screw. Since Andrew only uses experience, then Andrew considers
acceptable what is really unacceptable. Just another reason why
experience without learning fundamental technology results in
erroneous conclusions.

I very much doubt a wiring problem. Such a "loose screw" would
have different behaviour and either not manifest itself, or have
a much longer (probably although not necessarily permament) effect.
In any case the electrics are reasonably modern. Oh, and there's
been a time served electrician (my father) living in the house ever
since it was built.

Added to that, it's strange how these 'wiring problems' suddenly
become a lot more apparent in thunderstorms. Or gales for that
matter.
 
W

w_tom

True, but the 10% tolerance applies on a continuous basis only, it
does not cover transients. There's no question that the voltage
drops below this as the UPS does trip.

Power supply must work just fine when line voltage drops by 25%
continuously. It also must work just fine when voltages drop even
lower for less time. This is what it must do. Therefore power supply
will be even more resilient. For example, when voltage is lost for
maybe 20 milliseconds, then PC must work uninterrupted.

Why is that number important? Even UPS relays take 10+ milliseconds
to switch from a 'direct to AC mains' connection to 'battery backup
power' connection.

If AC electric has anomalies causing that unacceptable voltage drop,
then other appliances (ie microwave clock, VCR) will be flashing every
day - maybe within hours. Are you daily resetting the microwave
clock? Then problem is not inside a computer. Don't cure symptoms.
Fix the problem - defective AC wiring; defective utility, etc.
Computers are so robust that no daily power changes should ever affect
the computer.

Having said this, homeowners with AC receptacles connected by a rear
'push in' connection are all but asking for future problems.
Receptacles should have wires wrapped around screws. Simply remove
the cover plate to inspect. Wire should be obviously wrapped and
tightened by screws.

If AC electric creates a need for a UPS, then fix the grossly
unacceptable problem. UPS would only cure symptoms. UPS is not for
making hardware more reliable. UPS is for blackouts or extreme (long)
brownouts; for data protection.
 
M

mhaase-at-springmind.com

Hey w_tom!

Can I get your thoughts on this?

First, let me say that I, too, am a big believer in the use of the
multimeter (had one since I was 8), and now have a spiffy digital that
I use all the time.

My question is about detecting super-fast variations in output voltage
from a bad PSU. I've come across power supplies that will cause the
machine they're installed in to randomly reboot (confirmed this by
installing the same PSU in a different computer and seeing the same
reboot problem).

Now I assume this is happening because something in the PSU is causing
some kind of momentary power swing/fluctuation/drop/etc at it's
output. I'm guessing it's momentary/super quick, because the meter
shows all is fine.

So my question is: Is there anyway to use a meter to check for this
kind of failure?

Thanks!

M
 
S

Strobe

Hey w_tom!

Can I get your thoughts on this?

First, let me say that I, too, am a big believer in the use of the
multimeter (had one since I was 8), and now have a spiffy digital that
I use all the time.

My question is about detecting super-fast variations in output voltage
from a bad PSU. I've come across power supplies that will cause the
machine they're installed in to randomly reboot (confirmed this by
installing the same PSU in a different computer and seeing the same
reboot problem).

Now I assume this is happening because something in the PSU is causing
some kind of momentary power swing/fluctuation/drop/etc at it's
output. I'm guessing it's momentary/super quick, because the meter
shows all is fine.

So my question is: Is there anyway to use a meter to check for this
kind of failure?

No, not with conventional retail-type meters.
Digitals sample the voltage over time and could miss a spike/sag.
Analog meters have too much inertia to respond to short-term changes, though
you just might see the needle vibrate if the fluctuations were gross.

I did once use a galvanometer-type photo-recording voltmeter to track mains
supply fluctuations that were causing repeated computer crashes - but that's way
beyond what most people can lay their hands on. The size of single cycle
excursions from nominal were surprising. (BTW, back then we found our problems
included lack of grounding of the utility supply into the building!)

Hence, I'd suggest using a 'scope to monitor suspect voltages - but do remember
that mains supplies (whether 230 or 110) can be lethal.

I've been out of the business for 30 years; back then we had a few 'scopes that
could react to a trigger and record short periods of time and freeze it on
screen - is that now a standard feature on any affordable units?
 
K

kony

My 10% figure for perceived dip in illumination wasn't plucked from
thin air.

Regardless, it is not expected that a computer SMPS will
have any problems with AC voltage depression if there are no
observed problems with anything else at the location. If
one wants to do a lot of advanced measurements, great, but
as well it would be to just measure the output of the PSU
itself or try another one.
 
W

w_tom

...
My question is about detecting super-fast variations in output voltage
from a bad PSU. I've come across power supplies that will cause the
machine they're installed in to randomly reboot (confirmed this by
installing the same PSU in a different computer and seeing the same
reboot problem).

Now I assume this is happening because something in the PSU is causing
some kind of momentary power swing/fluctuation/drop/etc at it's
output. I'm guessing it's momentary/super quick, because the meter
shows all is fine.

So my question is: Is there anyway to use a meter to check for this
kind of failure?

Notice layers of filtering between fast transient generators and the
power supply. First, ceramic capacitors are scattered all over the
board; adjacent to all fast transient generators to bypass such
currents right at the source. More filtering electrolytics where
power is applies to the board. Then more inside the power supply.

Those fast transients are made irrelevant by the fitlering. However
slower frequency voltages also are not measured by most meters - often
called ripple voltage.

Notice numbers provided for voltages. 3.23, 4.87, and 11.7. These
are higher than what the actual voltages can be (3.135, 4.75, and
11.4). Voltages measured between those two values can actually be
dipping repeatedly below those lower limts. Above higher acceptable
numbers compensate for how meters work and for how power supplies
respond to higher frequency voltages that most meters cannot measure.
Add layers of filtering that must exist for all systems and those
microsecond type transients are made completely irrelevant.
 
M

Mark N

kony said:
If the PSU problem is intermittent, you're left detecting it
exactly when it happens. Do you have the facilities to do
this? For example an o'scope or fast logging multimeter,
though of course it can't be hooked up to the PC that is
resetting itself to do logging.

You might unplug the PSU from AC for a few minutes and then
open, examine it. With luck you might find visual
indication of a failure like vented capacitors, or if you
have a multimeter you can check things like shorted/open
rectifiers or switching transistors, cold solder joints.
Otherwise such an intermittent problem still leaves you
waiting to catch it happening again, as the parts can't be
totally unworking yet to be able to turn the system back on
at all.

In other words, there are only two real alternatives, either
you have the tools, ability, and patience to take apart your
PSU and apply various load and temp conditions to it while
logging the output quality, or you don't and can only test
or look for basic things before swapping in a different PSU.

Well, I've eliminated the PSU as a source of the rebooting problem,
swapped it out for another and the problem remains exactly the same.
Still rebooting regularly, sometimes very quickly before the BIOS
routine is fully run, sometimes after it's been running for an hour or
so, but always a problem and not noticeably getting worse. In the course
of installing the PS I rechecked all the connections and rechecked the
mobo visually, nothing new. Not sure where to go next...
 
K

kony

Well, I've eliminated the PSU as a source of the rebooting problem,
swapped it out for another and the problem remains exactly the same.
Still rebooting regularly, sometimes very quickly before the BIOS
routine is fully run, sometimes after it's been running for an hour or
so, but always a problem and not noticeably getting worse. In the course
of installing the PS I rechecked all the connections and rechecked the
mobo visually, nothing new. Not sure where to go next...


The thread is now pretty long and I've forgotten some
details but have you tried another video card? If not I
would try that next if you had another available - even some
really old PCI card, if for no other reason than that it is
easier (and cheaper, you can get such an old ~2MB PCI card
from a mom-n-pop computer shop or online surplus or ebay for
about $5 or less, if not free in some web for-sale forums
but for shipping cost), quicker, less expensive than buying
a replacement motherboard.

Similarly you can try ruling out other parts subtractively,
disconnecting them from the system and seeing if the problem
persists. I assume there are no unused motherboard
standoffs shorting the back of the case or loose wires or
memory, etc... some things are hard to speculate about
without having the system in front of us or knowing all
details of it's history. You could also pull the board out
and try it in a minimal config on a desktop - not on
ESD-safe surface as that conducts electricity on the back of
the board.
 
M

Mark N

The thread is now pretty long and I've forgotten some
details but have you tried another video card? If not I
would try that next if you had another available - even some
really old PCI card, if for no other reason than that it is
easier (and cheaper, you can get such an old ~2MB PCI card
from a mom-n-pop computer shop or online surplus or ebay for
about $5 or less, if not free in some web for-sale forums
but for shipping cost), quicker, less expensive than buying
a replacement motherboard.

Similarly you can try ruling out other parts subtractively,
disconnecting them from the system and seeing if the problem
persists. I assume there are no unused motherboard
standoffs shorting the back of the case or loose wires or
memory, etc... some things are hard to speculate about
without having the system in front of us or knowing all
details of it's history. You could also pull the board out
and try it in a minimal config on a desktop - not on
ESD-safe surface as that conducts electricity on the back of
the board.

I already tried another video card, no change. I've checked the memory,
including running memtest86, no problems there. Given that reboots can
happen very early in the boot cycle, that doesn't leave much. Power
supply is fine. I have a sound card and dial-up modem as PCI cards, and
I guess I could pull those. I haven't pulled the mobo yet, but perhaps
worth pulling it out just to make sure nothing's under it.

Strange behavior in the last 24 hours. Seemed like it was close to being
done, rebooting rapidly and then just POSTing with long beeps, then last
night it booted upo and stayed running. After a couple hours I restarted
after reconnecting my DSL modem, and it booted fine again. A couple
hours later I went to bed and left it on, it went into hibernation fine,
and started up fine this morning, ran fine for about four hours before I
turned it off. Came home tonight and right back into the same old reboot
pattern...
 
M

Mark N

Mark said:
kony wrote:
I already tried another video card, no change. I've checked the memory,
including running memtest86, no problems there. Given that reboots can
happen very early in the boot cycle, that doesn't leave much. Power
supply is fine. I have a sound card and dial-up modem as PCI cards, and
I guess I could pull those. I haven't pulled the mobo yet, but perhaps
worth pulling it out just to make sure nothing's under it.

Strange behavior in the last 24 hours. Seemed like it was close to being
done, rebooting rapidly and then just POSTing with long beeps, then last
night it booted upo and stayed running. After a couple hours I restarted
after reconnecting my DSL modem, and it booted fine again. A couple
hours later I went to bed and left it on, it went into hibernation fine,
and started up fine this morning, ran fine for about four hours before I
turned it off. Came home tonight and right back into the same old reboot
pattern...

So after a bit of that action on Sunday evening I got it to load
Windows, and that was it. Not a single reboot since, and everything
seems to be running fine. So maybe a bit of a short somewhere or the
like, but I never found a definitive problem. I may just be suffering
from a "symptom gap", but I ain't gonna go looking for trouble where
there is none. Not at the moment, anyway...
 

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