I have the mid 2014 15 inch retina MacBook pro, running sierra on it. I was using it in a room, then closed it to take into a mother room, when I opened the lid, all of a sudden the screen was flickering pinks, I could not get it to stop, I could still see the contents on the screen, and the trackpad pointer worked, but it flickered. I did nothing that I have not been doing normally already. I have a plastic case on it. I had to shut it down, and restarted it, and it seems to functioning fine now. I bought this mac in April 2015, I think it is out of warranty now. After starting up again, I ran tech tool pro on it and tested the video memory, and it passed. Are there any other apps to test with? I also run flux on it, if that could be a factor. also, this laptop has dual graphics; the Intel Iris Pro but in, and the NVIDEA GeForce GT 750 M, dedicated graphics.