Is there not a better way to replace the graphics card in my 2011 27" iMac? I have twice fixed the AMD Radeon HD 6770M graphics card using the 'cook' method: dismantling the motherboard, removing the card, cooking in the oven for 30 minutes and replacing the thermal paste etc. First time lasted about 18 months. I'm hoping for something similar again for the second cook. On each occasion the computer is working like new.