wrote:
On Apr 4, 9:49 pm, Paul wrote:
someone_else wrote:
Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.
When the power button is pressed the laptop fan whirs for about 2 seconds
and then nothing happens the screen is left blank, no further activity.
If I pull the power cable out, push it back in, then press the power button
the same thing happens,
However if I power down by holding the power button for 7 seconds (leaving
the power cable attached); the fan whirrs for 2 seconds as before, but then
the laptop appears to cut the power (as if it is overheating) ... then 2
seconds later the fan whirrs on as if the laptop is rebooting. Nothing
appears on the screen ..
I did manage to boot as far as the windows logo by leaving the laptop in a
cold room for an hour and then trying.
So you see why it points to overheating .. but on the other hand when I feel
the heatsink with my finger it does not feel too hot at all! (I had another
laptop overheat, and it felt hot alright)
any ideas?
A heatsink can be cold for two reasons.

1) It can be so well cooled, for the level of power being dissipated,
that it ends up having a low temperature.

2) If the heatsink is not making contact with the hot object, then
the heatsink will remain cold. That is my suspicion in your case.


Thanks for replying!

If the heatsink is not making contact would it not shut down in all
cases?
At the moment, the laptop does remain powered up, (but only after I
disconnect and reconnect the power), and with a blank screen.
Yesterday it got as far as the windows logo screen before it froze. If
it was overheating would it not shut down in that case?

I really need to try thermal paste in any case, there is nothing to
lose.

cheers!


So then maybe it is just freezing. If the power remains
running, but the screen won't update, then it could be
a freeze. It could even be just the display that is
frozen. (If the computer is networked with other
computers, you can try "ping" from another computer,
to see if it'll answer a ping request. If it answers,
then the processor on the laptop would still be
running.)

Freezing problems aren't that easy to debug - it could be
motherboard, CPU, RAM that is involved. Only in a few cases,
does it involve something like a bad driver. (Years ago, there
was a Marvell Ethernet driver that caused freezing.) But your
freezes are early in the boot process, so the drivers aren't
even running at that point. When the Windows desktop appears,
the drivers should all have run their initialization code
at that point. The fact that there is a time component
(runs longer when cold), suggests there is a thermal
component to it, but it still doesn't tell you what part
inside the thing, is at fault.

Tools you could try

1) Memtest86+ from floppy or CD (memtest.org)
2) Linux LiveCD from CD.
3) Booting DOS from a floppy or CD (there is at least one
CD image of a DOS floppy available out there)

My reason for recommending memtest86+, is not for the memory
test part. It is to see if a really tiny program can load and
run without freezing. Then, see how long the machine can run
with that test running. If it works, then you know that
memtest86+ doesn't use all the hardware in the computer.
It won't be trying to run the network interface, Wifi,
stuff like that.

DOS would be for similar issues - it might use a subset of
the hardware.

Linux would try to use everything, and I doubt you'd get
any further than Windows would. I only use that test case,
because I already have a number of CDs. I like older versions
of Knoppix (several of the 5 series), since they tend to write
text on the screen while they're starting up. When a computer
is unstable, the error messages printed in text during the
boot, gives you plenty of evidence to look at. Linux LiveCDs
that are silent during boot, are less useful.

Paul