I have this laptop with graphic card problem. The laptop starts normally but after 10 min the fan kicks in very fast and the laptop shuts down. I noticed with HWmonitor that the graphic chipset temp starts getting very high at 10 min up to 105 C. Tried different drivers but the problem the same. Is it cold soldering of BGA, can a reheat fix the problem. Any one with same problem or information for further troubleshooting.

Try another heatpipe.

-clean dust iinside the fan and change thermal pad/paste,
-if no luck, reheat may fix the problem,
-and if no luck too, reball/replacing the GPU is the solution.

actually i cleaned the fan house and reapplied new thermal paste. What is the best way of reheating, reflow or backing inside oven to be recommended?

I have no rework station so reflow with hot air gun or oven reheat are my chances to approach.

it's more safety to reflow it using hot air gun,
i not recommended backing inside oven, you may destroy it,
but you need to read this guide if you want to backing it in an oven.

At first, test with another heatpipe..

Reheated using a hot air gun gradualy under 10 min ( top temp 240 C in 30 seconds ), prior to that heated the whole pcb to 120 C on hot plate.

The board working fine now, no overheating problems using the same pipe. Shall see how long does this thing hold. Thanks for help.