Laptop problem

[AirShowNut]

Hi all.
I have been given an old laptop to do with as i wish.
It's a Fujitsu Amilo L7300.
When i was given it i was told that there was no power,either battery or mains.When i stripped it down i found the power connector socket was broken,which i replaced.I re-built the laptop plugged it into the mains and it fired up straight away.However,after only around three minutes the laptop sudenly dies,it is NOT overheating,the air blown out of the chasis is still cold,the fans run ok,i have tested the hard drive using a connector to my pc and all is well with it.I have checked,cleaned and re-seated all cards and memory modules too.Does a laptop HAVE to have a functioning battery in order to run ? I was always under the impression that they will run on mains supply quite happily.
Anyone have any ideas why the laptop switches off suddenly?
Any help or suggestions appreciated as it's doing my head in

[ricopicouk]

I know you touched on this in your post, but how do you know its not overheating? have you checked the contact point between the cpu and heatsync?

also, might want to try running a live os disc, to check its not an issue with the installed OS

[AirShowNut]

When i stripped the laptop everything,more or less,had to be removed including the heatsink and fan.All were cleaned,new compound put on and tightened down.As for the os,i have wiped the hard drive using a connector to my pc and i'm currently trying to re-install the os from cd.Personlally i think the memory is at fault,because if i leave the laptop when switched on without it trying to install the os then it stays on for as long as i want,ie no load put on the memory chips,as soon as i try to install the os it will turn off.All i need is someone to confirm my suspicion of the memory being at fault.Or point me to something else.
Thanks for the input,much appreciated.

[AbsoluteFire]

I'd go with memory fault if that is what you're seeing.

You could try out memtest86. I comes bundled on almost all the linux live CD's

[AirShowNut]

UPDATE !!!!!
Swapped out the memory modules for two which i KNOW are working (borrowed from son's laptop).And the same thing happens,so i've ruled out the memory.Just have to put it back in my son's laptop before he gets home from college.
Back to banging my head

[AirShowNut]

SOLVED !!!!!!!!
When i removed the memory modules to put them back in my son's laptop,i decided,for no reason,to put some more heat sink compound onto the processor heat sink.Lo and behold the laptop fired up and ran like a good un.
The moral ?
Never scrimp on the amount of heat sink compound you use.
Thanks to all who contributed.

[Messa]

SOLVED !!!!!!!!
When i removed the memory modules to put them back in my son's laptop,i decided,for no reason,to put some more heat sink compound onto the processor heat sink.Lo and behold the laptop fired up and ran like a good un.
The moral ?
Never scrimp on the amount of heat sink compound you use.
Thanks to all who contributed.

To be fair pal you must have just dropped lucky on the amount u used.

Putting too much on is just as unhealthy as not enough.