Hi, I've got a 15" MBP 2.5 GHz i7 (late 2011 model), with OSX 10.9.4 Since about two weeks, I'm experiencing graphics artefacts on the screen. I am aware of the 2011 MBP graphics problems as described here: http://www.macrumors.com/2014/01/17/2011-macbook-pro-gpu-glitches/ However, I'm not sure if it IS the graphics card that's causing the problem with my setup. I'd appreciate your input on this... The problem also occurs on my external screen so I don't think it's down to a bad connection between logic board and LCD. What's been happening pretty much once or twice a day is: 1) Wake up computer from sleep, start working. 2) At some point during the day I get graphics artefacts: weird patterns, vertical stripes, image "shifted" to the right, blinking individual pixels,... but the mouse pointer still moves 3) A few seconds later, the system freezes, mouse doesn't move any more 4) Turn off computer holding the power button for a few seconds 5) Wait 10 seconds or so 6) Restart 7) STRAIGHT AWAY, as soon as the grey screen with the apple logo comes up: graphics artefacts with vertical and horizontal stripes 8) apple logo disappears / screen goes grey with NO artefacts 9) Apple logo reappears, but looks a bit weird and "shifted" in a "2048 tile" puzzle kind of way 10) desktop appears, with absolutely NO artefacts whatsoever. 11) back to Step 2) The reason why I think it's NOT a GPU problem is: once the desktop and all desktop icons come up, the artefacts are gone. I work in GPU-intense applications (Adobe Photoshop, Keynote), and the artefacts/crashes appear really randomly. (i.e. NOT straight away when I work in Photoshop, but maybe after a few hours). Any ideas what it could be? (RAM would be the next thing to check I guess...) Am I correct in cancelling out GPU or could this still be the problem? If despite all hopes it IS the GPU after all.... does Apple recognise the problem & provide free logic board replacement (or at least a reasonably-prized one?) I bought the MBP as a refurb in June 2012, when the first retina models came out. Don't have Apple Care. Would really appreciate your input on this! Thanks a lot!