Don't forget the simplest explanation: eye tracking motion blur. At least that's what I've convinced myself as of late (I'm "experiencing" a similar issue as OP with my PG278QR.) Another way I'd describe it would be, when viewing the testufo, it would appear with the clarity of 2MS persistence and then suddenly transition clarity to that of 4MS persistence, only to revert back just as quickly as it started occuring — think of when old antenna TVs used to briefly display images of crossed signals.Chief Blur Buster wrote: TL;DR: You said your motion blur suddenly appears/disappears mysteriously. The "sudden appearance" of motion blur is sometimes simply a framerate-halving or framerate-quartering problem caused by a multimonitor setup. This is not always the cause, but unfortunately common. There are other causes (which we'll still have to sleuth) if this is not the issue.
Would that even be possible, dynamic persistence values? Based on the name, I'm leaning towards no