Graphical issues with el capitan

Please launch the Console application in any one of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

The title of the Console window should be All Messages. If it isn't, select

SYSTEM LOG QUERIES ▹ All Messages

from the log list on the left. If you don't see that list, select

View ▹ Show Log List

from the menu bar at the top of the screen.

Click the Clear Display icon in the toolbar. Then take an action that isn't working the way you expect. Select any lines that appear in the Console window. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of which is irrelevant to solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name or email address, may appear in the log. Anonymize before posting.

When you post the log extract, you might see an error message on the web page: "You have included content in your post that is not permitted," or "The message contains invalid characters." That's a bug in the forum software. Please post the text on Pastebin, then post a link here to the page you created.

If you have an account on Pastebin, please don't select Private from the Paste Exposure menu on the page, because then no one but you will be able to see it.

If your MBP has a dual GPU, which I think it does, you may be able to avoid the problem by disabling Automatic Graphics Switching (System Preferences > Energy Saver).

C.

P.S. I'm assuming this option is still present in El Capitan, I don't have dual GPU system with EC installed to actually check.

Clearly you are having GPU issues. I have no idea if it is a hardware issue, but it could also be a memory issue. The GPU does not have its own VRAM, and instead shares RAM with the CPU. How much it uses is contingent on how much available RAM there is, so the next question is: how much RAM do you have?

The logic board is faulty and will have to be replaced.

Make a "Genius" appointment at an Apple Store, or go to another authorized service provider. You may have to leave the machine there for several days.

Back up all data on the internal drive(s) before you hand over your computer to anyone. There are ways to back up a computer that isn't fully functional—ask if you need guidance.

If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.

Keeping your confidential data secure during hardware repair

Apple also recommends that you deauthorize a device in the iTunes Store before having it serviced.

*An SSD doesn't need to be zeroed.

That's my opinion based on the evidence I have. You don't have to, and should not, take my word for it. Have the machine tested by an Apple-certified technician.