Laptop randomly shutting off after seconds/minutes: not overheating

delta36

Hey folks,

Just come back from trying to fix a friends laptop, and I'm all out of ideas.
Basically, the laptop will switch off at random points, as if the power has suddenly been cut. Sometimes it'll happen a few seconds after switch on, sometimes it can be 30 minutes. After this happens the laptop will take a few seconds to a minute or two before it can be turned back on.
It's definitely not an overheating issue, the laptop stayed on long enough at one point for me to install CoreTemp, and the CPU cores were well below the shut off point when the laptop turned off.
It has two RAM modules, both of which I've tried individually in the laptop, and the same problem occurs.
It's a ~6 year old Dell running Vista. Using the on-board diagnostics report no problem, provided the laptop stays on long enough for them to complete. There's no weird clicky noises coming from it to indicate hard drive failure.
I've also tried running the laptop without the battery, it seems to make no difference.
As well as the turning off issue, occasionally, the keyboard will output characters which have not been pressed. For example outputting 5 when I press r, or outputting ó when pressing o. Furthermore, sometimes pressing backspace will just place more characters instead of deleting. I've run a virus scan for as long as the computer stayed on, and nothing came up.

The only other possibility I can think of is that the CPU could be covered in gunk after all these years, and that this could be causing all the problems (I recall reading a spyware horror story years ago where someone said their computer was acting oddly, had no malware, and cleaning the thermal paste and applying new paste fixed the issue). Is this actually possible? In that case would cleaning the thermal paste fix the problem?
Is there anything else that could be causing these problems? I've fixed computers and laptops for years in my spare time, and have never come across something like this. I'm all out of ideas, so any insight/help would be very much appreciated boardsies

billy few mates

I had something similar on a laptop in the past where it just kept shutting down randomly usually, but not always just after start up, as you can imagine it was a real pain to try and troubleshoot as the thing wouldn't stay on long enough to do anything. I initially thought it was an overheat problem but managed to eliminate that by sitting the thing on some of those freezer blocks and starting it with cold air blowing through the cooling vents so I was able to confirm the core temp was well below trip point when the thing shut down.
Eventually I ran out of ideas (and patience) so I brought it to my local computer repair shop where the guy told me he was 100% sure it was some sort of virus and that he would have to reformat it to fix it.
I wasn't too sure about that but I had no better ideas myself so I left it with him, I picked it up a few days later and it was working fine and I never had any further problems with it.

delta36

billy few mates wrote: »

I had something similar on a laptop in the past where it just kept shutting down randomly usually, but not always just after start up, as you can imagine it was a real pain to try and troubleshoot as the thing wouldn't stay on long enough to do anything. I initially thought it was an overheat problem but managed to eliminate that by sitting the thing on some of those freezer blocks and starting it with cold air blowing through the cooling vents so I was able to confirm the core temp was well below trip point when the thing shut down.
Eventually I ran out of ideas (and patience) so I brought it to my local computer repair shop where the guy told me he was 100% sure it was some sort of virus and that he would have to reformat it to fix it.
I wasn't too sure about that but I had no better ideas myself so I left it with him, I picked it up a few days later and it was working fine and I never had any further problems with it.

That's very strange. Would a virus be able to cause the laptop to shut off at the bios screen though? Before the OS has had a chance to start running?

looking_around

To me it sounds like a motherboard issue.

Placing new thermal paste could, and it isn't expensive so worth trying.

It doesn't sound like a virus issue (if you want to check though, simply connect a different HDD ..)

Have you opened up fully? Does anything look 'off' with the mobo? any swollen..uh transistors I think they're called. Anything that looks loose.
Did he spill anything on the lappy? Any residue left on the mobo? By the meyboard/keys?

delta36

Thanks for the replies lads, the laptop is off at Click at the minute, so hopefully they'll pinpoint the issue.

looking_around wrote: »

Have you opened up fully? Does anything look 'off' with the mobo? any swollen..uh transistors I think they're called. Anything that looks loose.
Did he spill anything on the lappy? Any residue left on the mobo? By the meyboard/keys?

I didn't give the motherboard anything more than a cursory glance as I was swapping out RAM, (and marveling at the build of the laptop. As an aside, I was very pleased to only have to take off one panel and the RAM, wireless card, CPU, GPU, heatsink and fan were all easily accessible), but I didn't notice any obvious burn marks, or any open capacitors. No, nothing was spilled on the laptop either.
From what you've said there, and further digging around online, I'm going to guess it's some power issue on the motherboard, hopefully Click can come up with a solution that doesn't just involve replacing it.

deadduck

hi there.

i know this is a quite a while ago, but i'm just wondering if you ever got anywhere with this. i've an asus (transformer t100) after developing an issue where it'll shut down after 30 mins exactly every time. Leave it on the BIOS screen or in Windows, exact same. And like your issue, all temps report OK before it cuts out??

i'm at a loss here. found a few other reports online about others with the same issue for my computer and other brands, but no comprehensive solution unfortunately

beauf

Boot with a live Linux CD. If it boots and stays on then its software. If not then its hardware.

deadduck

thanks for the reply, but does the fact that it happens when left sitting on the bios screen not indicate that it definitely is a h/w issue? tbh honest, i'd already decided it is a h/w issue, but was hoping someone knew what the fix might be, or the original OP might be able to tell us if he ever found out the root cause

beauf

Just realised you replied to a 3yr old post. My reply was at the OP. If yours is doing that after a hardware reset then it s hardware fault.

deadduck

beauf wrote: »

Just realised you replied to a 3yr old post. My reply was at the OP. If yours is doing that after a hardware reset then it s hardware fault.

Cool, thanks for the feedback

ED E

deadduck wrote: »

it'll shut down after 30 mins exactly every time.

Assuming no firmware updates or similar I'd say its the hardware clock. A bit rollover at whatever point could in theory nuke it.

You've replace the CMOS batt yeah? The consistent time makes me slow to think a failing cap or similar.

deadduck

ED E wrote: »

Assuming no firmware updates or similar I'd say its the hardware clock. A bit rollover at whatever point could in theory nuke it.

You've replace the CMOS batt yeah? The consistent time makes me slow to think a failing cap or similar.

From what I've read it doesn't have a seperate Cmos battery. I have opened up the case and disconnected the battery for a few minutes, but no change in behaviour