I have a radeon 5850 hd oc i never have problems with it exept when i try to plug in my tv in my second port.
in my hd port i have a benq 23 monitor and in my second dvi i have a tv
The problem with the flickering apears only when i plug in a second monitor or my tv, when i have only my main monitor i dont have any problems.Also the flickering doesnt stay on the second monitor/tv it changes eather from main monitor or tv/second monitor