Especially to those laptop users who experienced this problem (Black Screen = GPU Failure -one of the reason). What you should know is, every laptop are using built-in GPU. In simple word, the Graphic Card is attached to your laptop motherboard directly and can't be separate by any human (unless you use violence ??? ).
Why GPU failing??? Ok, the explanation is here. Earlier, I said your GPU is attached to your motherboard and can't be separated by any means. So it means something must be putting them together. The glue in electronic world is the solder.
Now we know about the solder. For your information, everything have its specific melting point. For this solder, the melting point is about 150 - 200 degree celcius. Check this out to know other solder melting point.
The melting point is low because of the use of tin based solder. It's cheaper than the other thats why they use it to attach a GPU to the motherboard and also attach other component to the motherboard such as capacitor.
Let us understand the condition of the solder on the motherboard. Let say you put an ICE cube on a plate, and heat it. It will melt right. If you cool it down to its freezing point, it will freeze again but lets observe its shape? does the shape of the ice cube same as before it melt? No right? So, basically, the same thing happen to the solder on your motherboard. Sometimes the heat exceed the melting point of the solder, so it will melt. But, when it cooldown and freeze, the shape maybe different. Maybe have tiny cracks that invisible to your eyes has occur. *** Even a tiny crack on the solder can make your laptop malfunction ***