My Early 2011 15" had that problem. Several times a day my screen displayed garbage and the whole computer froze up. If I manually switched to integrated graphics, it was fine, but if you connect an external display, it always switches to dedicated graphics. After a while it was impossible to boot the system, not even to recovery mode, or an external backup. Apple couldn't even run their own diagnostic software, because it froze before it loaded. I'm not on Apple Care, but they replaced the logic board for free. 😛 I've upgraded to the newest retina MBP since then, which is completely silent and cold to the touch even after a full day of work (I'm running multiple VMs all day). The 2011 model was like a vacuum cleaner, and you could fry eggs on it after 5 minutes. I can only recommend Haswell chips, they produce no heat whatsoever, and the average people don't need a dedicated GPU anymore.