First of all: THANKS MACHEAD3
The support here was very fast.
I finally solved the issue with my GPU.
It is indeed a problem with the soldering between logic board and GPU.
I used the guide to complete tear down the macbook pro here on IFIXIT, and get my hands on the logic board.
I separated the heat sink from the logic board, and cleaned up that thermo compound very sticked to the components (all gpu and cpu). I've polished them without scratch but until shine.
Than, I used a HAIR DRYER to sold the GPU again, like the tutorials on youtube for that.
I made up a mask with rought paper in order to centralize the heat over the square (3 x 3 cm) area of the GPU and kept about 10 minutes in hight mode with circular motions and 10 cm distance from the board.
I've waited it cool down (1 hour is more than enought).
I've applied the Arctic MX-4 (can I say brands here?) thermal compound on GPU and CPU and attached the heat sink back and mounted the notebook again.
Hopfully... all is working now for more than 1 weak. Pretty fast and most of all "COOL". I have 67º on CPU and 53º on GPU at the present moment. And I'm using Photoshop, illustrator, safari, firefox, calculator, excel, notepad and torrent client.
That's is a very bad manufacturing error from Apple. So if you make a hardware check, there is nothing wrong with the logic board or GPU. But it your system stress the GPU, the sooner it will get hot and will lead to the defective image transmission, until you cannot even startup correctly, even on secure mode (shift on start up).
This kind of DIY is not basic for sure.
Dismount the machine was not that hard, it is a great piece of technology, just have care and tools. Disconect the battery first of all... I did not took apart the DVD unit or the HD drive. just the logic board.
But take the computer mounted again, back to live.... oh man... that was kinda scary due to a connector behind the logic board, that is so tight when I put it back, that I could not reach it with my fingers... If someone is in a situation like me, know that this is kinda "basic" to solve, but you need patience and care (if you think you will be nervous... take to a professional and tell what is need to do, this is kinda comon in hight demanind cpus, gaming, and so on).
But maybe not much patience as wait Apple made a recall. They did for macbooks pro on 2010 with exactly the same problem. But the entire 2011 line is supost to have the same, there is more than 17500 signatures in a petition website with the same issue as mine.
I thanks again for the amazing tutorials here on IFIXIT, your prompt reply and all guys that made this toturials to help users like us. Hope someone in the same need as mine have found a quickly solution until Apple do what a fare company should.
Which graphics setup do you encounter the issue with? Intergraded graphics engine or the external GPU (AMD Radeon HD 6490M or AMD Radeon HD 6750M) and which one.