Hey, I opened up my rMBP, cleaned it all up and swapped the thermal paste. I noticed a great improvement regarding temperatures so I consider doing it a must. Anyway.. since I've done it, the integrated GPU is used a lot more than before where the dedicated GPU would almost always being used. The other day I was watching a 1080p video in YT and the HD4000 was being used for that where before, the 650M would always be the chosen one to do that. Is it possible that cleaning the insides of the rMBP and swapping the paste could have done this? Why? I don't think it was just coincidence..