I have had a GTX 970 for a long while now with no issues. I’m running Ubuntu 17.04 on Kernel 4.10. I’ve recently acquired a 4K monitor (X4071UHSU-B1) which is capable of 4K@60Hz over HDMI 2.0.
For the avoidance of doubt, I’ve reproduced this issue with multiple HDMI cables rated to 4K@60Hz (one purchased specially to eliminate this variable).
I was initially unable to use 4K@60Hz, but this post: https://devtalk.nvidia.com/default/topic/939971/4k-60hz-works-in-windows-not-in-linux-workaround-found-/?offset=29 enabled me to do so. However, I’m now confronted with another issue - any and all red pixels on the screen become pixelated. The results of this are as follows:
As can be seen, pixelation only occurs for red pixels, is specific to my 4K monitor, and disappears at 30Hz. I’m quite stumped by this issue - I attach my bug report log (edit: there doesn’t seem to be an option to upload, so https://www.dropbox.com/s/eg1m34vnwdnp31g/nvidia-bug-report.log.gz?dl=0).
The images illustrate only the most obvious example - but the effects are visible on almost any screen as a slight un-focusing of all of the on screen elements - due, I presume, to most of them having some amount of red on them.