Laptop powers off at random

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I'm looking into some problems with an HP Pavilion zt1130 for a friend.
 The problem, generally, is that the thing shuts completely off at
apparently random times.  I've been looking into this, and here are
some high level observations.

There doesn't seem to be a certain amount of time elapsed from boot
that the system tends to shut down.  It has run for a few hours without
issue; and it has shut down during login (XP).

There doesn't seem to be a direct correlation to system overheating, as
it's never been noticeably hot --relative to laptop heat issues anyway.
 Also, given the lack of a pattern of elapsed time noted, there are
times when it hasn't had a chance to heat up, and those when it
operates just fine long after it's reached peak or close-to-peak

There doesn't seem to be a correlation to any particular access point
on the harddisk or other hardware.  I ran some diagnostic tools (the
"eDiagnostics" HP bundles, as well as looking through Hardware
Manager), and aside from relatively minor suggestions, there weren't
any errors presented.  CHKDSK did say it found some errors, but I've
run all over the harddrive so it doesn't seem that those bad blocks are
necessarily the culprit.

There *is* a shadow of a pattern to be found, though: when cold
booting, the machine seems to work perfectly fine; but upon reboot, it
begins flaking out.  I'm going to test this a little more, but it holds
most of the time at least.  I had it running for hours the other day,
with no issue, and I tried to keep at least a little CPU load on by
having Windows show a slideshow of an image folder.  It wasn't until
the power was cut off (I had thought it might've been a flaky battery,
so I had it out to test) and the computer was then rebooted that 5
minutes afterward it flaked out.

Also, I ran it for a while a second time, from a cold boot a couple of
days later, and then rebooted (the right way), only to have the system
shut down a few minutes into booting up or right at login.  Subsequent
attempts to get the system to work also tended to end in shutdown.  A
couple of times, this happened while running the eDiagnostics stuff
before Windows had booted, so it doesn't seem to be an OS issue.  Also,
while once or twice the system shut down while running a system-wide
search for image files--which tempted me to think it was some file
corruption or something--repeating said search precisely only resulted
in finding the thousands of image files on the harddisk.

Since it's worked pretty well with and without the battery, I'm led to
consider one of two things, primarily: RAM; or something shorting on
the system board.  I would imagine that a short on the motherboard
would result in more regular flakiness--like either it works or it
doesn't.  I know that memory, though, is a fickle beast, having had all
sorts of goofy stuff happen with bad RAM in the past.

Short of dropping some PC-133 laptop RAM in the thing, or tearing it
apart to see the motherboard, are there any other angles I should
consider?  My friend has hinted that he doesn't really want to spend
much if anything to get the thing going, so $100 or so for 256MB fo
PC-133 might be a little steep for a 1.13 GHz Celeron machine, and
understandably so.  Still, if that can be verified as the culprit, then
maybe we hunt for someone with spare memory or something and see how
that works out.

Thanks for any help.


Re: Laptop powers off at random has 256MB PC133 for around $38 so it's not expensive online.

This sounds like an overheating problem more than memory and I would
suggest the following first before buying memory -

First - (if it has one which most hsf on laptops do) removing the
thermal pad on the hsf and using some thermal compound and see if it
helps any.  Just because the laptop does not "feel" warm or hot does
not mean the cpu is not cooking to death.  If the heat from the core is
not transfering to the heat sink material it will overheat without the
rest of the system getting warm. Being a celery 1.13 the laptop should
feel warm especially on the base and keyboard near the processor
because they generate good amounts of heat and everyone I work on is
very warm if transfering heat correctly.  The whole laptop acts like a
heatsink in a way on some models.

Second thing is check to see if the MB is cycling the fan.  If not this
could be a bad fan, pad thermal probe or a needed bios update. Also
blow out any dust or debree that might be hindering cooling.

Third - Memory, if it is flaky, will cause weird errors and BSD's more
often than just a simple shut-down.  I don't believe the memory is the
cause, but you might reseat the simms to check.

Fourth - All mobile Pentium III and Celeron mPGA, uPGA and MMC-2
processors have "speedstep" which is intel's speed throttle built into
the cpu for battery life. When the laptop is on battery power speedstep
runs the processor much slower, usually around 700mhz for a 1.13 and
decreased voltage, and thus causes less heat buildup from the processor
core.  This would explain why you say the system works better with the
battery alone.

Hope this helps!

Re: Laptop powers off at random

Thank you for a thorough response. wrote:
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Yeah, I wasn't sure if stock PC-133 would do the trick, or if there
were a special laptop form factor.

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I'll certainly check into that.

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I actually don't remember hearing the fan, which was cause for concern;
but since I hadn't felt the thing be too warm, I thought maybe it was a

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Can't hurt.

I actually haven't really tried it on battery alone.  Maybe I mistated
something.  The only configuration that had anything to do with the
battery specifically was its removal.  I have an older Dell laptop that
won't even boot if the battery's in it, so I thought this might be
another case of a crappy laptop battery.  I haven't run it on battery
alone, though.

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I think it will.  Thanks again.

Re: Laptop powers off at random

Sorry I misread the battery part. I thought I read it as you had tried
with a battery alone.

The ram stuff...

Older Dells, such as PIII 100MHz bus have to have PC100 ram installed.
PC133 will not work even though it is backwards compatable with PC100.
The bios is programmed to not take it. Now Dell's ( such as C8x and
8000's ) with a 133 bus chipset, weither the cpu installed is 100 or
133, will accept PC133 ram.  Why Dell did this I will never know.  It's
a pain.  I haven't had this issue so far with other brands but I
wouldn't be suprised.  They all use SODIMM memory.  The only physical
difference is SDRAM or DDR/DDR2.  SDRAM is 144pin and the DDR is 200

If your older Dell had the problem of only powering on without a
battery installed, then it is a problem with either the DC jack, power
supply (very unlikely) or the power board ( if it used a seperate board
for this function, some do, some don't ) and since the power goes
through the battery, it will back feed to the motherboard.  No laptop I
have refurbished so far has needed a battery in the system to operate
unless there was a problem with either of the above mentioned things.
I know this is not your current problem but I thought you and others
might be interested in this information.

Might also suggest a bios update.

Sometimes there are bugs with reguards to cooling and fan cycling that
they fix even if they ( the manufacturer ) don't say so.  I had a sony
vaio with an Duron 900 that would crash and freeze in WinXP.  I knew
there was a bios update specificly for XP but didn't think it was a big
deal.  After getting sick of rebooting and crashes, I updated the bios
and it fixed everything.  The most noticable thing was, the fan ran
almost all the time and at high speed.  I knew it was heat related
because I had made it better with removing the thermal pad and
replacing with silver thermal compond.  But that alone didn't cure the
issue totally.  So even though Sony said it was for XP compatability,
it was more of a cooling fix than anything.

Re: Laptop powers off at random

Just to add to my post...

All intel chips have a built-in shutdown when they reach a certain
temperature to keep from melting or catching on fire.  This will
trigger the shutdown described and will be random due to random loads
thus causing random heat build up.

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