The 2011 Macbook Pro 15″ and 17″ both suffer the same inherant  issue of a bad Radeon graphics chip which is a manufacturing defect. It may present it self with lines on the screen as pictured, or a pale grey screen with nothing on it, or mid boot the screen goes black or grey. There are some repair outfits that will ‘reflow’ the chip thus resoldering it fully back onto the logic board – This is only a very temporary fix. The correct and permanent fix for these is to disable the disctrete Radeon graphics chip forever where it will then utilise the integrated graphics. With the Ram maxed out at 16GB with a Solid State Drive, these are still beast machines and lightning fast. We can offer this logic board repair which retains screen brightness control, but will lose the ability to connect an external display. The turn around is usually less than 2 days.