Just got a Gainward 5900 non-Ultra 256 MB today (review will be up later today, first non-Ultra with 256 MB me thinks, pretty wild performance)
It has both the flickering issue AND the mouse wheel issue.
Though there's no consistency, the issues just come and go as they please.
Turning off smooth scrolling did nothing for me when it comes to the mouse issue.
Pretty funny that the mouse wheel bug makes the actual videocard make noises. Sounds like short bursts electrical surges.