Macbook Pro Display - Green Flicker only when Photoshop etc is open I have a 2011 Macbook Pro and I've suddenly been having this recurring problem of black pixels appearing green and flickering...

Firstly, if I have no software open and "Automatic Graphics Switching" ticked, in the Energy Saver preferences, it stops the flickering and the display is fine. If I untick it, the flickering green appears again.

Unfortunately the moment I open any software, like Photoshop, Buildbox, SketchUp etc, the green flickering starts and displays, even if the "Automatic Graphics Switching" is ticked or not.
The moment I close the software, and if the "Automatic Graphics Switching" is still ticked, the display is normal.

What's even WEIRDER, is that if I mirror my screen onto a Monitor, and open Photoshop of example, the Macbook Pro display/black pixels still flicker green but the monitor renders/displays everything perfectly fine.
If I close the software, the flickering stops an displays normal.

So... What's going on?

Is it the display or the graphics card?
Surely if its the graphics card, the mirrored monitor would display flickering pixels too?

Also, I did a Hardware diagnostics and the only error was the Battery (which I bought off Amazon 6 months ago).
My mac is fully up to date with El Capitan.

Help me please 
Thank you so much.
Sounds like the beginnings of a GPU failure - there is an active repair program that runs through the end of the year for the 2011 MBP, so get your machine to the Apple Genius Bar and ask for a VST test.  Good luck! 

https://www.apple.com/support/macbookpro-videoissues/