A few of us also posted this issue in another thread:
At first I thought it was memory artifacts, as they look similar. I don’t think that’s the case, since it only seems to happen with motion and the top part of the screen. The Nvidia 3000 series also have error-correcting memory modules, so they won’t throw artifacts.
This thread seems to highlight it’s an issue with render scaling and/or TAA on Nvidia cards. This could be a driver-related issue as well.