A step-by-step guide on how I successfully swap the graphics card to K1100M on my 2011 27″ iMac and install Catalina in this unsupported system. I decided to take on this project due to the infamous Apple AMD GPU failure so that I can continue getting life out of my iMac. This process applies to my own system, which may or may not work exactly the same for other systems with different specs. Credit to those in this thread over at MacRumors for making this project possible.