I have a late 2012 mac mini (2.6GHz Core i7 16GB Intel HD Graphics 4000 1536 MB) running OS X 10.11.2
For months now, I get flashing color bars on my display-port-connected 21:9 LG Ultrawide running 2560 x 1080 @ 60 Hz.
If I logout and back in, the bars go away for a day.
What could be going on?
Mac mini, OS X El Capitan (10.11.2), Late 2012, 2.6GHz Core i7 16GB
Does it happen with another mini displayport-connected monitor?
- Try resetting the SMC and NVRAM/PRAM
Intel-based Macs: Resetting the System Management Controller (SMC)
- Try starting in Safe Mode
OS X: What is Safe Boot, Safe Mode?
- Boot to Recovery and repair the startup disk
OS X: About OS X Recovery - Apple Support
- If it is repairable reinstall the OSX
How to reinstall OS X on your Mac - Apple Support
- If you do not have a backup use disk utility to restore the internal disk to an external disk so you can try to recover data.
Then format the startup disk and do a fresh install of OSX
Screen flashing bars - logout fixes for a day
