On Sun, 5 Apr 2009 01:48:08 +0100, "someone_else"
wrote:

Hi all,
I received a laptop to fix today .. It behaves like it is overheating but
I'm not sure.

It's always good to start out mentioning the specific make,
model, spec of the hardware.



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.

But the laptop remains powered, LEDs lit at least?



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 ..


You mean when you try to turn it on again after holding down
the power button for 7 seconds, or that it tries to start on
it's own without your having pressed the button?

Is the battery still installed at this point or you have no
battery or it won't hold a charge, or ??



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)

Not necessarily overheating, it might be or it could be a
bad solder joint or crack elsewhere on the PCB, especially
considering laptops are subject to a lot more stress than a
desktop.

What is the history of the system? Has anyone else mucked
around inside it? Generally speaking the heatsink interface
won't go bad all by itself, it would require someone to take
the 'sink off and try to reuse the thermal interface
material again if it's a phase-change waxy pad instead of a
silicone rubber pad.

When it feels cool, is this always when it shows no response
on-screen or does it also feel cool when you are able to get
it to start booting windows? If it has had the battery
installed all this time, try it without the battery, and
vice-versa, if you'd been using the AC adapter try charging
the battery and using only battery power.