Since 3 days ago, after I updated Photoshop CC, overtime I use Photoshop, it suddenly starts pixelating all over the screen and then it gets frozen totally. I cannot even press Option Command Esc to force quit. It is madness. The whole screen, and mouse is frozen. My iMac is a 16gbRAM, 2.8GHz Intel Core i7. Anyone knows what is happening?
Sounds like you are hitting some of the video driver bugs in MacOS 10.10.
You can disable GPU drawing in Photoshop, then restart the app.
But if you need the GPU features, consider downgrading to a more stable version of MacOS.
Which model GPU are you using?
We're still gathering documentation on the driver bugs for Apple.