My MBP Late 2011 15" has been experiencing major graphics problems. One day I was on my MBP then it suddenly turned off and horizontal blue lines appeared all over the screen. Everytime I try to boot I only get to half way. However i did manage to get into my system 1 time and managed to wipe my MBP and install Sierra, but then you can guess what happened. The MBP would run so smooth and fast but as soon as i opened a cpu heavy programme such as (Ableton Live or Final Cut Pro) it would freeze up with glitched lines all over my screen. Sometimes even turn off then suddenly come back on. The things i have done are; Reset my mac to factory reset. I have changed my hard drive from a 500MB to 1TB. Took out my 8GB of ram and tried booting but no joy. Commands such as (cmd+s) (cmd+v) only end up freezing within a minute. I have literally tried everything, I done some research and people have removed their logic board and cleaned their GPU and CPU then heated the chips up and applied more fresh thermal paste. However I don't have a heat gun and really don't wanna try those things if there is another way. Could someone help me out, thanks guys!