turns out it was a defective cable. Swapped that out and flickering was gone. Always nice to have the latest drivers though so not all a waste. Uninstalled CCC as that appears to have a memory leak.

On a side note, you can detect flickering easier with your peripheral vision. Since it's a 50" TV, when reading webpages, I open the browser only on one side of the screen, leaving the other half empty or a second browser. That's when I noticed the flickering most.