For those who have GPU issues with the Macbook Pro 2011 15” or 17” there’s a way to disconnect the NVIDIA GPU and only run with the Intel integrated GPU. You can solder a small board on the logic board rom chip, this product is the Tiresias GPU Killer. That will permanently desactivate the NVIDIA GPU. I tried it on the 15” model motherboard 820-2915 and on the 17” model 820-2914 with success. Video out will also be desactivated after the job is done but the computer will work just like the MBP 2011 13” who doesn’t have the NVIDIA GPU.
http://www.cmizapper.com/products/tiresias-gpukiller.html